why no edit button ?
Because you have endless opportunity to 'edit' your THREAD information, before you hit the POST button.
If users were allowed to 'edit' THREAD info, titles, etc., things would quickly spiral out of control.
The ADMIN MODS are very good at responding to a request to 'correct' a headline. IIRC, the fast/best way to do so is to HIT the ABUSE button yourself (meaning the 'poster' of the thread) and explaining your need in the abuse post.