So I stumbled across this by accident, and haven't been able to replicate it since. A couple of weeks ago when I made a post about indoor skiing in Boston, I double clicked the thread title, and it highlighted the text, similar to how you can highlight the text of a folder in Windows to rename it. It let me change the thread title, and saved it when I pressed enter.

I can't do that anymore though, even to that one thread it worked on before. Was this some sort of setting that was temporarily changed, or is there any way for us lowly mortal AZ'ers to change the title of a thread we started?