Make sure that you always change your birthday, even if it’s a wrong one, to 13 years of age or older to be able to change it at a later date. How to change your age on Roblox account (PC desktop)?

ROBLOX allows you to change this username, as well as your Display Name. It’s important to note that there are different rules and applications of both Usernames and Display Names.

How Can I Change My ROBLOX Display Name? You can change your Display Name for free, once every seven days. This is how other players see you in-game and isn’t unique to one player.