Windows 10 file association selection
Solution 1:
There are a couple ways you can do this to workaround that limitation you wrote about where it doesn't let you select other apps to associate, etc. but I'll write a simple solution you can use.
Create a dummy file with the extension you wish to associate with a specific program if you don't have an actual file already (e.g.
test.region) right-click on it and select Open With
When the How do you want to open this file? window pops up, ensure that the option Always use this app to open <
.ext> files is checked and then select More apps
You will then have a scroll bar that you can navigate to select the app you want the file to open with if it's listed. Otherwise, at the bottom of the scrollable list you can select the option Look for another app on this PC. Then when the Open with window opens you can navigate the file system and find the app you want the file to open with and double click it and you'll be all set.
Further Resources
- How to Fix the Missing “Open with” Option on the Windows 10 Right-Click Context Menu
- How do I set a default app for an extension that is not listed?