Roblox allows all users to change their Roblox account's display name in the account settings without spending a dime. Here's how to do it.

Steps for altering your avatar’s appearance in every Roblox experience, from adding and removing items to changing your skin color and gender.

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.