1. Open Security

    Go to /dashboard/security.

  2. Turn it on

    Click Turn on. You may be asked to confirm your password or Google account first.

  3. Scan the QR code

    Scan it with an authenticator app such as Google Authenticator, 1Password or Authy, or enter the setup key manually.

  4. Confirm

    Enter the 6-digit code from the app. From now on, signing in asks for a fresh code.

The Security page also lets email accounts change their password and shows recent sign-ins and security changes, so you can spot anything unexpected.