This sounds like a local issue with a browser editor script.
In other words, as this doesn't affect anyone else, then it's an issue with your software. So please can you try:
1. Use another browser and see what happens.
2. If the other browser works fine, then it looks as if there is a glitch on the first browser, related to the script it uses to edit online forms.
if you can get to that point then please let us know - thanks.