1. Open the File Explorer in Windows 10 by clicking on the folder icon in the bottom left corner of your screen.
2. Choose which type of file you want to change the default program for by highlighting it.
3. Right-click on the file and select “Open with” from the context menu.
4. Select either “Choose another app” or “Choose default program” from the menu that appears.
5. Choose from the list of available programs to open the file with. If the program you want is not listed, click Browse to look for it elsewhere on your computer.
6. If you chose “Choose default program,” check the box next to “Always use this app to open [file type] files” if you want the new program to be used automatically whenever you open a file of this type.
7. Click “OK” to save your changes.
Your new program should now be the default program used when opening files of the selected type. This should apply both to single files as well as any files of the same type in a directory. To change the default program for a different file type, repeat the steps above.