With the new Microsoft Windows 10 updates, it’s no longer possible to change to another editor other than Notepad. File associations to for .txt seem to be locked on Notebook. So, here is the solution.
I know that lots of developers and people with more IT background would not use notepad. I mean, notepad? Come on, what the heck — this is 2021, not 1992. That’s why more modern and sophisticated text editors are out there such as UltraEdit. However, Microsoft things that everybody must use Notepad, and that’s why it’s no longer possible to associate the .txt file extensions with anything else then Notepad. What do we think about that? A**holes! Exactly.
Step 1: Change File .txt Associations to WordPad
Windows allows you to change the .txt extension after all. Since Notepad is a solid part of the Windows now, first thing you have to do is to get off Notepad, and switch to WordPad. Don’t worry, we won’t be using WordPad, we will do this only to trick Windows. So go ahead and do this:
Press CTRL+X and go to “Settings”. Search for “file” and select “Choose a default app for each type of file”:

Scroll down to the extension .txt and change that to WordPad:

In this screenshot you can see that I have UltraEdit in there already. But selecting it won’t do anything good as all txt extensions still open with Notepad. You can try of course and if that solves your issue, than you can stop here. But you are probably reading this, because that didn’t work. So go ahead and select WordPad.
Next, go to your UltraEdit, right click it, and start it as Administrator.
On UltraEdit go to Settings/File Associations and add .txt under “File Types/Extensions:

Click apply.
Almost there.
Now go to your Test.txt file, right click it and choose “Properties”:

Now click “Change” and for wonderous reasons, it will now allow you to change the file association for .txt to anything you like, such as UltraEdit.
If you feel grateful for this solution, I appreciate a comment. Thank you!
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