You double-click a PDF and it opens in Preview when you wanted Adobe Acrobat. Or every image launches Photos instead of the editor you actually use. On a Mac, the app that opens a file is called its default app, and you can change it in about ten seconds — either for one file or for every file of that type, permanently. Here is how, with no Terminal and no downloads.
Change the app for one file only
Use this when you just want to open a single file in a different app this one time — without changing anything else.
- In Finder, right-click (or Control-click, or two-finger tap on the trackpad) the file.
- Hover over Open With in the menu.
- Pick the app you want from the list.
The file opens in that app right now, but the next time you double-click it, it goes back to the original default. That is the point of this method — it is a one-time override.
App not in the list? Click Open With → Other…, then browse to the app in your Applications folder. If the app appears greyed out, tick Enable: All Applications at the bottom of that window.
Make it permanent for every file of that type
This is the setting most people actually want: from now on, every .pdf (or .jpg, .docx, .txt — any type) opens in the app you choose.
- Right-click any file of that type and choose Get Info (or select it and press Command‑I).
- In the Info window, expand the Open with section.
- Pick your preferred app from the drop-down menu.
- Click the Change All… button just below it, then confirm.
That is it. macOS now opens all files with that extension in your chosen app until you change it again. The Change All… button is the whole trick — skip it and you have only changed that single file.
Set your default web browser
Links from Mail, Messages, and other apps open in your default browser. To switch it from Safari to Chrome, Firefox, or another browser:
- Open System Settings (Apple menu → System Settings).
- Go to Desktop & Dock.
- Scroll to Default web browser and choose your browser.
On macOS Monterey and earlier this lives in System Preferences → General instead. If your choice keeps reverting, we cover why in our dedicated guide: how to change the default browser on a Mac.
Set your default email app
When you click an email link (a mailto: link), it opens in your default mail app. Change it here:
- Open the Mail app (yes, even if you plan to switch away from it).
- Go to Mail → Settings → General.
- Change Default email reader to Outlook, Gmail-in-a-browser helper, or another installed mail client.
The setting is tucked inside Apple Mail even when you want a different app to take over — that catches almost everyone.
Frequently asked questions
How do I stop PDFs from opening in Preview on my Mac?
Right-click any PDF, choose Get Info, expand Open with, select your PDF app (Acrobat, PDF Expert, etc.), and click Change All…. Every PDF will open in that app from then on.
Why does Change All not work?
Two common reasons: you did not click Change All… after picking the app (just choosing from the drop-down only affects that one file), or the file has an unusual extension so macOS treats it as a different type. Confirm the file’s real extension in Get Info, then repeat on a file with that exact extension.
Can I reset a file type back to the Apple default?
Yes — open Get Info on a file of that type, pick the original Apple app (Preview, TextEdit, Photos, etc.) under Open with, and click Change All… again.
Does changing the default app delete the old one?
No. It only changes which app opens that file type. Both apps stay installed, and you can still open a file in the other app anytime with the one-file Open With menu.
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