Could have sworn I've always been able to change the titles of my own threads. I just go to the forum page that the thread's in (In this case it'd be The Bell Tree HQ) and then double click just to the right of your thread's title.
I'm a mod on another site, and it's so easy to forget how to do things "normally" after being one for a long time, isn't it? And when I'm on other sites, I end up looking for options that aren't available to me.