Create an account so people can actually tell it's you — usernames are unique and messages are tied to your login, not just a typed-in name.
Already have an account? Log in
Pick a username, a password, and (optionally) a photo.
Notifications tell you about new messages and calls, even when the app is closed. The microphone is for voice messages and calls. You can change both later in Settings.
For your security, changing your username requires your current password.