For Windows:
You can right-click one file > Open with >Choose another app > and choose what program you want to use>Click Alway use this program to open PDF file. Then, all files will be opened with the program you choose.
For Mac:
1. Select any PDF file from Finder. Control-click to open the menu.
2. Choose Get Info from the menu that opens.
3. From the Open with: section in the new window that opens, select your preferred application.
4. Click the Always Open with>Open.
