If a PDF suddenly opens in a browser, an image opens in the wrong editor, or a text document launches an app you never use, the file itself may be completely fine. macOS stores an association between file types and the applications that normally open them, and that association can change after installing, updating or removing apps.
Use Open With when you want a different app only once. Use Get Info > Open with > Change All when you want every file of the same type to use a new default. Those two actions solve different problems, and mixing them up is the most common source of confusion.
Open one file in a different app without changing the default
- Find the file in Finder.
- Control-click or right-click it.
- Choose Open With.
- Select the app you want to use for this file now.
This does not normally change the default for every PDF, JPG, CSV or other file of the same type. It is useful when you want to inspect one document in a different program.
Change the default app for an entire file type
- Select a representative file in Finder.
- Choose File > Get Info, or press Command-I.
- Expand the Open with section.
- Choose the application you want.
- Click Change All.
- Confirm that you want documents of this type to open with the selected app.
The important button is Change All. Choosing an app in the Open with menu but not applying Change All can leave other files using the old association.
One file still opens differently from all the others
A single document can behave differently if its individual association was changed or if the file is not actually the type you think it is. Use Get Info and check the file name and extension. A file called report.pdf is different from a web link, alias or package that merely has a similar icon.
If Finder is behaving inconsistently in other ways as well, compare the symptom with Can’t Drag and Drop Files on Mac? before assuming the file association is the only problem.
The app you want is missing from Open With
First confirm that the application is installed in the Applications folder and can open normally. Then open the app itself and try File > Open with the document.
If the app cannot read the format, macOS may not present it as a normal compatible choice. The problem can also occur after an incomplete app update or when two versions of the same app are installed in different locations.
Open With shows duplicate apps
Duplicate entries can appear after migrations, backups, external drives or multiple app versions have been indexed. Before trying to reset anything, check whether you genuinely have two copies of the application. Search Applications and any attached external disks.
If the duplicates appeared together with broader Finder or indexing problems, it is useful to check whether Spotlight is seeing the system correctly. See Spotlight Not Finding Apps or Files on Mac?.
PDF files open in the browser instead of Preview
Select one PDF, open Get Info, choose Preview under Open with and click Change All. If PDFs then open in Preview but cannot be saved or exported, that is a separate permissions or document problem. Follow Preview Can’t Save or Export a PDF on Mac instead of repeatedly changing the default application.
Images open in an editor when you only want a quick preview
There are two separate workflows on macOS. Pressing the Space bar uses Quick Look and does not require changing the default app. Double-clicking a file launches its associated application. If Space produces a blank preview or no preview at all, troubleshoot Quick Look separately with Quick Look Not Working on macOS Tahoe?.
What if Change All does not stick?
Work through the problem in this order:
- Confirm the chosen app still exists and launches.
- Try a local file in Documents or Desktop rather than a cloud-only file or read-only disk.
- Check that the extension is visible and correct.
- Restart Finder or log out and back in if the UI appears stale.
- Test a newly created file of the same type.
If only old files are affected, compare their Get Info details with a new working file. If every file type is opening unpredictably and other Finder functions are broken, the issue may be broader than one file association.
Do not rename an extension just to force another app
Changing .jpg to .png, or .pages to .docx, does not convert the file. It only changes the name. The contents remain in the original format and may become harder to open. Use the application’s Export or Save As function when you need a real format conversion.
FAQ: default apps on Mac
How do I open a file once with another app?
Control-click the file, choose Open With and select the application. That is the safest option when you do not want to change the default for all similar files.
How do I make Preview the default for all PDFs?
Select a PDF, choose Get Info, set Preview in Open with, then click Change All and confirm.
Why does a file have the correct extension but still refuse to open?
The document may be damaged, incomplete, protected, encoded in an unexpected format or simply unsupported by the selected app. Try a second known-compatible app before changing system settings.
Will changing the default app modify my files?
No. Changing the association changes which application launches when you open that type of file. It does not convert or rewrite the documents by itself.