On the main Roblox page, click the gear icon in the upper-right corner of the screen and select “Settings.” On your Settings page, click the edit button (which looks like a pencil on a sheet of paper) beside your username. In order to change your username, you’ll need to have a verified email address as well as 1,000 Robux.
Changing Your Username
On Roblox, you can change your account's username in the account settings. It costs Robux to make this change. However your Display Name is a free option to change how your name appears in an experience or game.
How do I change the username?
Log into your account
(If you can't log in, try these steps for recovering your password .)
Past Names
A list of previous usernames can be found on the Account Settings and Profile pages, along with People search. You can change back to a previous username, using the above method, which also costs Robux.
Via a browser
View by hovering over the Previous Group Names text on the group details page or under the current name in search results.
Via the app
View by tapping the Previous Group Names text on the group details page or under the current name in search results.