The new app lets you change your username once.
How: go to Settings → Account security → Change username, enter the new username and confirm.
Rules:
• 3–16 characters: letters, digits, underscore (_), hyphen (-) and dot (.).
• It can't be the same as your current username.
• You can only change it once, so double-check before submitting.
• Sign in with the new username afterwards; your plan, traffic and expiry date are unchanged.
Binding or changing your email is also under Account security. It now happens in a dialog where you can choose how the email is sent and resend the code, and it refreshes automatically when done.
