Updated: 02-24-2022
Usernames are account names players choose when signing up for an account. Each username is unique and cannot be registered again once another player signs up with it.
At this time, there is no way to change a username. Instead, we have designed a system where players can choose a nickname that is highlighted in areas of the website and game.
See also: Changing Your Nickname (https://worldtobuild.com/help/article/15)