Opening TXT files in Notepad instead of Monodevelop

When I open a text file from the Unity Project window, it opens in Monodevelop.

When I open the same text file from Windows Explorer, it opens in Notepad (the default program for text files).

How can I set Unity to open text files with my computer's default program instead of Monodevelop, while continuing to open cs files in Monodevelop?

I looked at Edit/Preferences, but could not find anything specifically for txt files. I found an option for "external script editor", set to Monodevelop, and "image application", set to "open by file extension". I'm guessing txt files are covered under "script editor".