Reason I ask is that there’s a thread in XJ :
“A/C does not work. Any and all help appreciated”
that should be in XJ40 
If you can see a pencil next to the thread title, then that means that you have edit permissions (either you started the thread, or you have moderator permissions).
If you click on the pencil you can edit the title, and there is a category selection list just below the title, which you can use to move the topic to another category.
(That was just for info, I’ll move the thread now, thanks for pointing it out.)