how can i make users change their thread titles

[kh99]

You could try this: create a plugin using hook global_start and code like:

if ($forumid == X)
   $vbulletin->options['editthreadtitlelimit'] = 0;

where of course you'd replace X with the forumid of the forum where you want unlimited title editing.

I haven't tested this so I'm not 100% sure it will work.