Changing your Username in Roblox will cost you 1,000 Robux, equivalent to $14.98. Whereas, the display name feature debuted in 2021 which is different than changing your username.

In-game, the display name is how someone will recognize other players. This feature debuted in 2021 and is open to all gamers at no cost.

Gamertag, username, display name; a Roblox player has multiple names, each having a purpose. Thankfully, usernames and display names chosen years ago can be changed.