How to undo an action

I don’t know what I did to cause this. Entering text in a document changed from a black default colour to “gold” colour.
If I backspace over the characters, the cursor backs up and nothing happens. If I try to delete, pushing the delete key moves the cursor forwards changing the next characters from black to gold. Highlighting the characters and then pushing delete moves the cursor forwards.
Changing the font colour has no effect. Clearing direct formatting changes all characters to gold colour.
Exit the program without saving reverts the file to original copy before the unwanted changes happen. Any typing is just the same problem as mentioned. Any suggestions?
Ian

Hi

You may accidentally have activated edit mode: EditTrack ChangesRecord Changes

Regards