South Lanarkshire Jag's post in Renaming a thread you have started. was marked as the answer
The original creater of the thread can still edit the thread title. Simply edit the opening post of the thread and it'll give you the option to amend the title. The only "moderation" options you'll have is delete(which is where edit title used to be[I think])
I spent ages trying to find out how to do it as well until i stumbled onto it!