This is a question that comes up fairly often and it's pretty relevant to this forum in particular since LP information can change pretty frequently, so I've decided to go ahead and make a quick topic to cover it. It's not really obvious how to do it because of how weirdly structured IPB is, but you should be able to edit the topic title as long as you are the OP.
- Go to the first post and click the edit button on it.
- Click the Use Full Editor button.
- The topic title should be visible and editable in the full editor. Change it however you like and then click Submit Modified Post when you are finished. The topic title should be changed.
Hopefully this helps you all.