You double-click a PDF and it opens in the wrong program: a web browser, a tool you uninstalled last year, or an app that freezes on large drawings. The fix is to change the default PDF viewer, and it takes under a minute once you know where the setting lives. This guide covers Windows 11, Windows 10 and macOS, plus the three problems that most often undo the change.
Change the default PDF viewer on Windows 11
- Open Settings (Windows key + I) and go to Apps, then Default apps.
- In the search box at the top, type .pdf.
- Click the app shown under .pdf and choose the PDF viewer you want from the list.
- If your app is not in the list, choose Choose an app on your PC and browse to its program file.
Faster route: right-click any PDF, choose Open with, then Choose another app, pick the viewer, and click Always.
Change the default PDF viewer on Windows 10
- Open Settings, then Apps, then Default apps.
- Scroll down and click Choose default apps by file type.
- Find .pdf in the list, click the app next to it, and choose the viewer you want.
The right-click route also works: Open with, Choose another app, tick Always use this app to open .pdf files.
Change the default PDF viewer on a Mac
- In Finder, select any PDF and press Command + I (or right-click and choose Get Info).
- Open the Open with section and choose the app.
- Click Change All… and confirm. Every PDF now opens in that app.
Three problems that undo the change
| Symptom | Cause | Fix |
|---|---|---|
| PDFs from email or the web open in the browser | The browser shows PDFs itself instead of downloading them | Chrome: Settings, Privacy and security, Site settings, Additional content settings, PDF documents, Download PDFs. Edge: Settings, Cookies and site permissions, PDF documents, Always download PDF files. Then open the downloaded file. |
| The default changes back after an update | A PDF program re-registered itself during its update | Set the default again; in that program's preferences, switch off any "make default" or "check default" option. |
| Your app is missing from the Open with list | The app did not register itself for .pdf files | Use "Choose an app on your PC" (Windows) and browse to the program, or "Other…" in the Mac Open with menu. |
Which PDF viewer should be the default?
That depends on what you open most. For office documents, the viewer built into your browser or operating system is fine. If you open large construction or engineering drawings, the default matters more: a viewer that stalls on a heavy sheet makes every double-click slow. We built Ncored in our architecture studio for exactly that case: it opens drawing sets of 50 MB and more fast and stays smooth when you zoom and pan, and it measures to scale and compares revisions.
- Mac: Ncored appears in the Open with menu for PDFs, so the steps above work directly.
- Windows: choose Choose an app on your PC and browse to
C:\Users\<your name>\AppData\Local\Programs\Ncored\Ncored.exe. Ncored installs for your user account, which is why it lives under AppData rather than Program Files.
Frequently asked questions
How do I stop PDFs opening in Microsoft Edge?
Set another app as the default for .pdf in Settings, Apps, Default apps, and in Edge set PDF documents to always download, so links you click are saved and opened in your default app.
Why does my PDF open in Chrome?
Chrome shows PDFs in the browser by default. Switch on Download PDFs in Chrome's site settings, then open the file from your downloads.
Can I use different PDF viewers for different files?
Yes. Keep one default and use Open with when you need another app for a specific file.
Related: why won't my PDF open, PDF won't open in Chrome, opening large PDFs fast on Windows.