Is it safe to delete preferences on a Mac? Why it backfires

Is it safe to delete preferences on a Mac? An app usually survives it, but it's rarely a good idea, and it's never a way to free space. The .plist files in ~/Library/Preferences are your apps' settings. Deleting one frees a few kilobytes and puts the app back to how it was the first time you opened it.

What goes with it is worth far more than the space: the choices you made in the app's settings, its window positions and layouts, and anything else the developer chose to keep there. Apple tells developers not to touch these files directly, because macOS keeps preferences in memory and writes them back on its own schedule.

There's one good reason to remove an app's preferences: troubleshooting, when the app's developer suggests it, with a backup and the app quit. Many apps, Apple's Final Cut Pro among them, have their own reset that does it properly.

This post explains what's in the Preferences and Saved Application State folders, why clearing them backfires, when a reset is the right fix and how to do one safely.

What's in your Preferences folder

Your Library folder has a Preferences folder full of small files, most named after an app's bundle identifier, such as com.example.app.plist. To see it, hold down Option in Finder, choose Go › Library, and open Preferences. The post on hidden files on a Mac explains why the Library is hidden in the first place.

What is a .plist file?

A property list: a small file of settings, each a name and a value. Apple's developer documentation calls the system behind them the defaults system, a persistent store for app-specific and system-wide settings that apps read to decide how to look and behave.

Apple describes where an app's file goes: currently in a Library/Preferences folder, named after the app's bundle identifier. The same page tells developers not to modify the file directly.

What kinds of settings are in them?

Whatever the app chooses to remember. Apple's examples include app-specific configuration and settings that apply to every app, such as the language the Mac uses. Its guide also notes that windows store their current position there, so they reopen in the same place.

So a single app's file can hold the options you set in its Settings window, the layout you arranged and much more. None of it is visible from Finder, and none of it comes back by itself once it's gone.

Why are there so many files you don't recognise?

Every app you've opened, every helper and extension that came with one, and many of macOS's own services keep settings there. Apple's documentation describes settings an app shares with its extensions, so a single app can account for several files.

Most belong to apps you've tried once or forgotten about. They're harmless, and together they still add up to only a few megabytes.

Is there a set of settings shared by every app?

Yes, in effect. Apple describes a global set of settings that applies to all apps on the Mac, which macOS provides and apps can't change. Settings such as the language you use live there.

That's one more reason not to clear the folder wholesale: some of what's in it isn't any one app's settings, but your account's.

Where do sandboxed apps keep theirs?

Not always in your main Preferences folder. Apple says the folder an app's preferences go in depends on whether the app is sandboxed: a sandboxed app, such as most apps from the App Store, has its own home inside a container.

The post on containers and group containers shows where that is: a Data folder with its own Library, including Preferences. If you can't find an app's settings file, look there.

Who reads the files?

macOS does, on the app's behalf. Apple's developer documentation says that when an app writes a setting, it updates its copy in memory straight away and writes the value to disk later. The files are where macOS keeps settings between launches, not something apps or people are meant to edit.

Place	What it holds	Who changes it
~/Library/Preferences	Your apps' settings, one file per app	The apps, through macOS
Inside an app's container	A sandboxed app's settings	That app, through macOS
~/Library/Group Containers	Settings a developer's apps share	Those apps
~/Library/Saved Application State	Windows an app reopens	The app, through macOS
/Library/Preferences	Settings for every user of the Mac	macOS and installers

Is it safe to delete preferences on a Mac to free space?

No, because there's no space to free. Preferences are among the smallest files on a Mac, and clearing them trades your settings for a few megabytes at most.

How big are preferences files?

Tiny. On one Mac measured in October 2026, the Preferences folder held about 2,900 .plist files, which added up to 4.4 MB. The largest single file was 2.3 MB. Most were a few kilobytes or less.

The folder itself measured more, because one command-line tool had stored a 111 MB folder of its own there. That's a tool putting data in the wrong place, not preferences, and it's rare.

• All 2,900 preferences files4.4 MB
• The largest preferences file2.3 MB
• npm's download cache, for comparison933 MB · Safe

One Mac, measured read-only in October 2026. Your numbers will differ; the gap between them won't.

Then why do cleanup guides mention them?

Because they look like clutter: thousands of files with odd names, many from apps you no longer use. Lists of so-called "junk" sometimes include them for that reason. The post on Mac cleanup scams covers the tactics that make small, harmless files look like a problem.

When space is short, the post on "junk files" and what they really are is a better place to start. Caches, downloads, old backups and developer files hold gigabytes; preferences hold kilobytes.

Does removing preferences make a Mac faster?

No. Preferences are settings, not work the Mac is doing; removing them only means apps start over with their defaults. Nothing about the Mac gets faster, and you spend the next week putting your settings back.

What you lose when you delete an app's preferences

Deleting a preferences file is a factory reset for that app's settings. Apple's Final Cut Pro guide puts it plainly: any custom settings go back to their defaults.

The choices you made

Every option you changed in the app's Settings window and, in many apps, the warnings you told it not to show again. Some apps keep a lot there; some very little. You won't know which until it's gone.

Window positions and layouts

Apple's guide notes that windows store their position in the defaults system, so they come back in the same place. A reset puts every window back where the developer first placed it.

Licenses and sign-ins

Apple tells developers not to keep personal or sensitive information in preferences, which are stored unencrypted, and to use the Keychain instead. So a well-behaved app doesn't lose a password when its preferences go.

Where an app keeps a license or an account's state is the developer's choice, and it's rarely documented. Before you reset an app you paid for, find your license key or check how the developer restores a purchase.

What isn't lost

Your documents. Apple's Final Cut Pro guide says resetting preferences doesn't affect libraries, projects or media, and documents you saved in your own folders aren't in Preferences either.

What goes with a preferences file	Can you get it back?
Options from the app's Settings window	Only by setting them again, or from a backup
Window positions and layouts	Only by arranging them again
Dismissed warnings, in many apps	They come back until you dismiss them again
A license kept in preferences, if any	Re-enter it; keep the key handy
Passwords kept in the Keychain	Not affected
Your documents	Not affected

Preferences, caches and app data: how they differ

People clear preferences because they sit next to caches in the Library and look just as disposable. They're different kinds of thing, and the catalog the app on this site uses treats them differently.

Folder	What it is	Clear it for space?
~/Library/Caches	Data apps keep to load things faster	Safe: apps recreate it
Caches inside app containers	The same, for sandboxed apps	Safe
~/Library/Application Support	Libraries, databases, downloads and settings	Review first
~/Library/Containers	A sandboxed app's data, settings and caches	Review first
~/Library/Preferences	Settings	No; there's nothing to gain
~/Library/Saved Application State	Windows an app reopens	No; there's nothing to gain

Why are caches different?

A cache is a copy of something the app can make again. The catalog describes app caches as data apps keep so they can load things faster, which they create again when they need it. Clearing one costs some speed while it rebuilds, and nothing is lost.

A preferences file is the only record of choices you made. There's no original to rebuild it from, so removing it loses them.

Do apps keep settings anywhere else?

Often, yes. Apple's developer documentation lists configuration files among what apps may keep in Application Support, and the catalog's entry for that folder mentions settings alongside libraries and databases. The post on the Application Support folder goes through what's usually in it.

So removing an app's preferences file doesn't always reset the app completely, while removing more of its folders risks your data. That's another reason a reset built by the developer is the better route.

Why deleting a preferences file may not even work

macOS doesn't read an app's preferences file every time the app needs a setting. That makes deleting one less predictable than it looks.

macOS keeps preferences in memory

Apple's developer documentation says that when an app writes a setting, it updates the copy in memory right away and writes it to disk later. Its guide to the defaults system adds that apps cache these values and catch up with changes at intervals.

So the file on disk and what the app is using can differ for a while. Delete the file while the app is running, and the app may carry on with its settings in memory, and write them out again later.

Apple says not to touch the files

The same documentation is direct: don't access the defaults database's files from the file system. Changing one directly, Apple says, may cause data loss, a delay in changes being available, or an app crash.

That's from Apple's guidance for developers, but it applies just as much to someone deleting files in Finder. Removing a file behind an app's back is exactly the kind of change it describes.

What this means in practice

If a developer asks you to remove a preferences file, quit the app first, completely. Then the file is the only copy, and removing it does what you meant. It's also why an app's own reset, which runs inside the app, is the more reliable way.

Saved Application State isn't a cache either

Next to Preferences, your Library has a folder called Saved Application State, with one item per app. It holds the windows an app reopens after you quit it or restart the Mac. Like Preferences, it's tiny and it's state, not a cache.

Why do apps reopen their windows?

So you can carry on where you left off. Apple says apps and their windows may reopen when you log in or open each app, and gives several ways to control that, none of which involves deleting files.

How do you stop windows reopening without deleting anything?

Apple lists these:

1. For one launch: hold down Shift while you open the app. It forgets the windows that were open when you last quit, without changing any settings.
2. For every app: choose Apple menu › System Settings, click Desktop & Dock, and turn on Close windows when quitting an application.
3. At restart: deselect Reopen windows when logging back in in the dialog that appears when you restart, shut down or log out.
4. For apps that open at login: check whether the app is a login item, and remove it from the list if you don't want it.

Apple adds that starting up in safe mode and then restarting normally makes the Mac forget which apps and windows were open, again without changing settings.

What you want	Apple's way	Does it change settings?
One app to open without its old windows	Hold Shift while opening it	No
No app to reopen windows	Close windows when quitting an application	Yes, one setting
Nothing to reopen after a restart	Deselect Reopen windows when logging back in	Remembered for next time
An app to stop opening at login	Remove it from login items	Yes

Is it ever worth deleting?

Not for space, and rarely for anything else. The Shift key does the troubleshooting job, for one app, without touching a file. If a developer specifically asks you to remove an app's saved state, quit the app first and move the item to the Trash, so it can come back.

When resetting an app's preferences is a real fix

Sometimes an app's settings really are the problem: it crashes at launch, a window opens off-screen, or a setting got into a state the app can't recover from. Resetting its preferences can fix that. The trick is doing it in the right order.

Try Apple's steps first

Apple's article on apps that stop responding or quit unexpectedly lists the steps: quit and reopen the app, restart the Mac, install updates for the app and macOS, delete and reinstall the app, and contact the developer. Deleting preference files isn't on it.

Most problems end at one of those steps. A restart or an update fixes far more than a reset does.

Look for the app's own reset

Apple notes that some apps offer an uninstall, remove or reset feature as a menu item or setting. A built-in reset is written by the people who know which files the app uses, including any in its container.

Final Cut Pro is Apple's own example. Its troubleshooting guide has you note your settings in Final Cut Pro › Settings, quit, then hold Command and Option while opening the app and click Delete Preferences. Apple puts it eleventh of thirteen steps, after updates and compatibility checks.

Test in another user account first

Apple's Final Cut Pro guide suggests a gentler test before any reset: create another administrator account on the Mac and try to reproduce the problem there. If it doesn't happen in the new account, settings or files in your own account are likely the cause.

Nothing in your account changes while you test. You learn whether a reset is worth doing before you lose anything.

Signs your settings are the problem

A few clues point at an app's settings rather than the app itself:

• The problem happens in your account but not in a new test account.
• It started right after you changed a setting or connected a new device.
• The app opens, but always in the same broken state: a window off screen, a missing panel, a setting that won't stick.

Windows are the easy case: hold Shift while opening the app first. For the rest, a reset is a reasonable next step once updates and a restart haven't helped.

If the developer tells you to remove the file

Follow their instructions, which name the exact file. If they leave the steps to you:

1. Make sure you have a recent backup. The post on backing up before a cleanup covers the quickest ways.
2. Note the settings you'll want back.
3. Quit the app completely. If it has a menu bar item or a helper, quit that too.
4. In Finder, hold Option and choose Go › Library, then open Preferences, or the app's container for a sandboxed app.
5. Find the file named after the app's bundle identifier, and move it to the Trash. Don't delete it outright.
6. Open the app and check whether the problem is gone.

If the problem is still there, the preferences weren't the cause. Quit the app, open the Trash, select the file and choose File › Put Back to restore your settings.

Preferences on other Macs, a new Mac and work Macs

Preferences belong to one account on one Mac. That shapes what happens when you remove them, move to a new Mac or use a Mac someone else manages.

Do preferences sync between your Macs?

Not through the defaults system. Apple's developer documentation says the system stores these settings locally, on the current device, and points developers to a separate iCloud store for data meant to follow you between devices.

So removing an app's preferences on one Mac doesn't touch your other Macs. An app that syncs its settings through iCloud or its own account may bring some back, but that's the developer's design, and it varies from app to app.

Do they move to a new Mac?

Yes. Apple says Migration Assistant transfers documents, apps, user accounts and settings from one Mac to another. Your preferences are part of why a new Mac feels like your old one from the first day.

They're also in your backups. Apple's documentation says backups include apps' stored settings, and a Time Machine backup can restore a preferences file you removed and emptied from the Trash.

Can you copy preferences to another Mac yourself?

It's better not to. Apple tells developers not to modify the defaults files directly, and copying a file over one an app is using is that kind of change. Migration Assistant moves settings the supported way, and some apps can export their own settings; check the app's menus or its help.

What about a Mac your work or school manages?

Apple describes a managed set of preferences that an administrator provides for a managed Mac. It's saved on the Mac, and apps can't change it. Deleting files in your own Library doesn't remove those settings.

If a work Mac has a setting you can't change, ask whoever manages it. Removing preferences won't get around it.

Does reinstalling an app reset its settings?

Usually not. Dragging an app to the Trash removes the app, not its preferences, so a reinstalled app finds its old settings and carries on with them. That's convenient most of the time, and why a reinstall doesn't fix a problem that lives in an app's settings.

Preferences left behind by apps you removed

Delete an app by dragging it to the Trash, and its preferences file usually stays. Apple's article on uninstalling apps says deleting an app doesn't remove documents or other files you created with it, and that an uninstaller, where the app has one, is the best way to remove the data it stored elsewhere.

Are leftover preferences worth removing?

For space, no: each is a few kilobytes. They're settings files, not programs, so nothing runs from them.

There's one reason to keep them: if you reinstall the app, it finds its old settings and picks up where you left off. That's often what people want after reinstalling.

What does an uninstall remove?

When you uninstall an app on purpose, removing its own preferences is reasonable: you've asked for the app to go, and its settings go with it. The post on leftover files after uninstalling apps lists every place an app leaves files and which of them hold your data.

Apps themselves are usually the bigger story. The post on apps taking up space covers what each app and its support files really weigh.

How can you tell whose file it is?

By its name. Most preferences files are named after the app's bundle identifier, the reverse-domain name its developer chose, such as com.example.app. The same identifier appears in the app's folders in Caches, Application Support and Containers, so it ties them together.

To check a file without opening it, select it and choose File › Get Info. You'll see its size and when it was last modified; a file changed today belongs to something you used today.

Files that start with com.apple belong to macOS or Apple's apps. Leave those alone; they hold the Mac's own settings.

Mistakes to avoid with preferences

Most damage done to preferences comes from treating the whole folder as clutter. These are the ones that cost people the most time.

Emptying the whole Preferences folder

Every app goes back to its first launch at once, along with many of macOS's own settings for your account. It frees almost nothing and costs hours of setting things up again. The post on what's in the Library folder explains why Preferences is one of the folders to leave alone.

Deleting from /Library/Preferences

That folder holds settings for every user of the Mac, written by macOS and by installers. Changes there affect everyone, and some need an administrator to undo.

Deleting with Terminal

A command that deletes files doesn't use the Trash, so there's no Put Back. If you're following a guide that asks you to paste a command to clear preferences, stop, and use the app's own reset or Finder instead.

Deleting while the app is open

As Apple's developer documentation warns, the app may still hold its settings in memory and write them back, or misbehave. Always quit first.

Trusting a tool that calls them clutter

A tool or guide that suggests clearing Preferences to free space is counting kilobytes as if they were gigabytes. The post on whether you need a Mac cleaner at all explains what macOS already handles by itself.

A worked example: an app that won't behave

Say a photo editor starts opening with its main window half off the screen, and its tool panels missing. Its owner's first instinct, from a forum post, is to delete its preferences.

Starting gently

They hold Shift while opening the app, as Apple suggests. The app opens without its old windows, in its default layout, and the panels are back. Nothing was deleted, and every setting is intact.

If that hadn't worked

They'd restart, then check for an update to the app and to macOS. Next, they'd look in the app's menus for a reset option, or search its developer's support pages, since the developer knows which files the app uses.

If a reset were needed

With a recent backup and the app quit, they'd note their settings, then reset with the app's own option, or move its preferences file to the Trash as the developer describes. If the problem stayed, they'd put the file back with File › Put Back.

What they didn't do

They didn't empty the Preferences folder, touch Saved Application State for every app, or paste a command. One app had a problem, and only that app's settings were ever at risk.

A second case: an app that crashes at launch

Say a different app quits the moment it opens. Its owner works down Apple's list: restart the Mac, then update the app and macOS. It still crashes.

They make a new administrator account and open the app there, as Apple's Final Cut Pro guide suggests. It opens fine, which points at something in their own account, likely the app's settings. They check the developer's support pages, find a reset option, use it, and the app opens. Only then do they set it up again.

How the app does it

Wombit scans your disk, reading only names, sizes and dates, and explains every item in plain language. File names and paths never leave your Mac.

App preferences and saved application state aren't caches, so Cleanup never offers them to free space. No catalog entry treats them as something to clear, and items no entry explains are never offered for removal.

Containers and group containers, where sandboxed apps keep their settings with their data, are Review first: explained, never checked for you, with what removing them costs.

• ~/Library/Containers/*

  App containers

  The private folder a sandboxed app, such as most apps from the App Store, uses as its own home for data, settings and caches.

  Review first · Explained only: the app shows you how

• ~/Library/Group Containers/*

  Group containers

  Shared folders where apps from the same developer, and their extensions and widgets, keep data they all use.

  Review first · Explained only: the app shows you how

The Applications section lists every app with its size and what it has left around the Mac, with Uninstall….

When you remove an app, the review pre-selects the leftovers that are useless without it, its preferences and saved state among them. Application Support, Containers and Group Containers start unchecked. Everything goes to the Trash, where Undo and Put Back work.

Seeing all of this is free. Cleanup and the uninstaller are PRO: one payment of $4.99 with lifetime access. Every Pro tool's review is free to open, so you see what would go and why before you buy.