Bud - that's in the "Moderator's Book of Secrets".
(Actually, only mods and admins can use that method to edit a thread title after the timeout period which is the main reason he can't get the edit to propagate to the index page.)
Greg - the reason you can't edit a thread title is because the edit window is only about 12 hours long. After that time, you can edit the title, but it is only the post title you are editing. It won't show up in the forum thread listing.
That is one reason we implemented the function for members to close their own Gun Show threads. See item #3 in the Gun Show rules thread. A closed thread is a very good external indicator that the sale is done, withdrawn, etc, in fact, it being one of the forum rules, we insist that members do it. Give it a try.