- Go to Account → Security.
- Press Enable 2FA and scan the QR code with an authenticator app (Google Authenticator, Aegis, 1Password, Authy).
- Type the 6-digit code to confirm.
- Store the backup code somewhere safe; it is the only way back in if you lose the phone.
From then on every sign-in asks for a code after the password. You can disable it from the same page.
