1. Tap Settings (the gear icon) in the top right corner of the screen.
  2. Tap the Link button (the + icon) in the top right corner of the screen.
  3. Tap the Call of Duty button from the options provided.
  4. Once the browser opens, enter your email address and password and tap Login Now.
  5. After successfully logging in, you'll receive a message saying, "Login successful. Log in using your Call of Duty account" and the game will relaunch.
  6. Tap Call of Duty at the login screen to log in to your account.