MyBB Community Forums

I changed the username of this user and then searched for his threads. He had two unapproved once, both show his old username without a link as last poster while the other threads were updated.
Note: those were also the only threads without a reply so that may be the cause but I didn't have the time to test this more.

Since both threads are in a moderated forum, I don't think it has anything to do with username change. Check:
http://community.mybb.com/thread-159141-...pid1111528
http://community.mybb.com/thread-159141-...pid1111636

Not sure, as said hadn't the time for more checking. It seems not to check the uid and use the username column instead. (Which should be updated on username change but afair we didn't do this in 1.6 too)