I can’t remember how i have made all my .txt files executable in ubuntu, so that whenever i double-click any .txt file or open the right-click menu, it only appears to run the file instead of trying to open it with text editor applications.

I can see an option "allow executing file as a program" in the file properties is checked, but i can’t uncheck it by click (it automatically gets checked again).

I have tried the following command but it doesn’t work:

chmod -x *.txt

How can i revert my txt files configuration back to normal behaviour?