To change your username, follow these steps:
- Tap on "Menu" and then "Settings"
- In the "Account" section, tap on your username
- There you will see your current username; if you tap on it you can enter a new one
- Finally, tap on save and your new username will be registered
Keep in mind that the username cannot have capital letters and must be unique, that is, it cannot already belong to another user.
If the one you want to add is already in use, you'll get an error message. If this happens, try adding a number at the end.