I don't see the problem...
I just did what you want to do in This Thread
Is that what you are trying to do?
All I did was click on the edit link on the upper right of the post and edit the title in the edit box.
You can edit the title at the very top of your post, but not the thread title that appears in the search results. That requires editing the thread, which requires a moderator. (Every post can have a title; the first one defaults to the thread title.)
It's probably not worth the effort. Just be sure you come back and reply saying you have solved the problem.