While you cannot in fact sign from Facebook Messenger, there are a couple of things that you can do to customize how you appear and exactly what you get in Messenger.
Ọ bụ ezie na ịnweghị ike ịbanye na Facebook ozi, e nwere ihe ole na ole ị nwere ike ime iji gbanwee otú ị si apụta na ihe ị nwetara na ozi.