TextEdit keeps changing file extensions when I save

Question

Is there a way to prevent TextEdit from changing the file extension on a file that I open it with, or at least prompt me?

Example:

1. Open somefilename.yyy
2. Save becomes somefilename.rtf

I have looked through TextEdit preferences without finding a setting.

Answer 1

Try with making the file to an Plain text file. It's under the Format tab (not in preferences).

Have you taken a look at this?

Apple support page