It could be two things, one fop related, and the other freepbx related.
1) fop2 related: go to freepbx, fop2 buttons page, click "refresh labels" button at the bottom, check if the names are shown correctly in the fop2 buttons page after that, and then log into fop2 and verify the change
2) if you still see old names, then it is a freepbx bug, where queue members mantain the old name, you can verify by issuing this command:
asterisk -rx "queue show"
Inspect the output, if you see old names for some queue mebers, then that is the problem, you have to edit the queue, remove the members, add them again and apply changes.