There are two different ways to change your username.

• While you are in a team, you can tap on the “Settings” button at the upper right corner of the home screen and tap on the “Change Username” button to change your username.
• At the upper left corner of the home screen, click on the "Profile" button, and then tap on your "Avatar." After that, you will see the "Edit Profile" menu, where you can change your username.

Don’t forget that you can change your username only once.