How to Change the Default App for File Types on Mac

Whenever you double-click a document, image, or media file in macOS, Finder automatically launches Apple’s built-in default application—such as Preview for PDFs, TextEdit for plain text files, or Music for audio tracks. While Apple’s pre-installed tools are reliable, you may prefer opening PDFs in Adobe Acrobat, code files in Visual Studio Code, or video files in VLC Media Player.

While you can right-click any file and select a different app from the “Open With” menu, that only changes the application for that single instance. To permanently change the default program for all files of that type across your entire system, you need to use macOS’s native Info inspector. In this guide, we walk through how to change default applications for specific file extensions on Mac, configure default web browsers and email clients, and clean up duplicate app entries.

How to Permanently Change Default App for a File Extension

To ensure that every file sharing a particular extension (such as .pdf, .docx, .mp4, or .png) opens in your preferred program by default:

1. Open Finder and locate any file with the extension you want to reassign.
2. Right-click (or Control-click) the file and select Get Info (or highlight the file and press Command + I).
3. In the Info panel that opens on the left, locate the Open with: section. If the section is collapsed, click the grey disclosure triangle next to it to expand it.
4. Click the dropdown menu displaying the current default application.
5. Select your preferred application from the list. If your app is not listed, click Other…, browse to your Applications folder, choose the app, and click Add.
6. Click the Change All… button situated directly below the dropdown menu.
7. A confirmation dialogue box will appear asking: “Are you sure you want to change all similar documents to open with the application…?”. Click Continue.

From this moment forward, double-clicking any file with that format anywhere on your Mac will automatically launch your newly selected application.

Changing the Default App for a Single Specific File

There are instances where you want general files of a type to open in one app, but wish to lock a single unique file to a specialised editor (for example, keeping standard .html files opening in Safari, while locking one specific HTML file to TextEdit):

1. Right-click the specific file in Finder and select Get Info (Command + I).
2. Expand the Open with: section.
3. Select your desired application from the dropdown menu.
4. Do not click the “Change All…” button. Simply close the Get Info window.

macOS will remember this override exclusively for this individual file, while all other files of that type continue using the global system default.

Setting the Default Web Browser and Email Client

Global protocols such as web links (http://, https://) and email links (mailto:) are not tied to specific file extensions on disk. Consequently, their defaults are managed through System Settings:

Changing the Default Web Browser

1. Click the Apple menu in the top-left corner of your screen and select System Settings.
2. Click Desktop & Dock in the left sidebar.
3. Scroll down to the Default web browser section on the right.
4. Click the dropdown menu and select your chosen browser (such as Google Chrome, Brave, Firefox, or Microsoft Edge).

Changing the Default Email Client

1. Launch the native Apple Mail app on your Mac.
2. In the top menu bar, click Mail > Settings… (or press Command + ,).
3. Select the General tab.
4. Locate the Default email reader: dropdown at the very top.
5. Choose your preferred email client (such as Microsoft Outlook, Spark, or Thunderbird).

Fixing Duplicate or Broken Apps in the Open With Menu

Over time, installing app updates, beta builds, and external drive backups can pollute the macOS LaunchServices database. You may notice identical duplicate app names or old, uninstalled applications lingering in your right-click “Open With” submenu. You can rebuild the LaunchServices database cleanly using Terminal:

1. Open Terminal via Spotlight (Command + Space and type Terminal) or from /Applications/Utilities/.
2. Paste the following command on a single line and press Enter:

   /System/Library/Frameworks/CoreServices.framework/Frameworks/LaunchServices.framework/Support/lsregister -kill -r -domain local -domain system -domain user

3. Next, restart Finder to refresh all cached context menus by running:

   killall Finder

The “Open With” list will reset to a clean, accurate inventory of currently installed applications.

Frequently Asked Questions and Troubleshooting

• Why is “Change All…” greyed out? The button is disabled if you have selected multiple files at once, or if you select the app that is already configured as the global default. Select a single file and ensure you choose an alternative application from the dropdown.
• Why does macOS prompt that an app cannot be verified? If you select an application downloaded outside the Mac App Store that hasn’t been notarised, macOS Gatekeeper may block it upon first launch. Open System Settings > Privacy & Security, scroll down, and click Open Anyway to authorise the application.
• Do external drive files follow these defaults? Yes. Default application bindings are stored locally in your Mac’s user preferences, so files opened from external USB drives, network shares, or cloud folders will adhere to your Mac’s default configuration.