How do you change the thing above reputation?

[Volixia669]

I'm new to the site and want to know. I've seen people with "onion kid" "shinigami" and some other cool stuff in my poking around. I just want to know how I can change it from "Registered User"

[Leon Scott Kennedy]

Settings->My Settings->Edit Profile->Custom User Title

[Volixia669]

Thanks!