On the website, open security settings and turn on two-factor authentication (sometimes called 2-step verification or "authenticator app"). In Authenticator tap + › Scan QR code and point your camera at the code, or choose Enter setup key if the site shows a key. Type the 6-digit code back into the website to finish.
In Google Authenticator tap ⋯ › Transfer accounts › Export accounts, select accounts and tap Next. In Authenticator tap + › Import from Google Authenticator and scan the code (or pick a screenshot). Keep Google Authenticator until you've checked that every code works.
Turn on iCloud Sync (Premium) to keep accounts on all your devices, or export an encrypted backup in Settings. Restoring an encrypted iPhone backup also brings your accounts to a new iPhone. Always save each website's recovery codes: they're your way back in if you lose every device.
Premium is $9.99 per week after a 3-day free trial (prices may vary by country). Manage or cancel anytime in Settings › Apple Account › Subscriptions. To restore a purchase on a new device, open Authenticator › Settings › Restore Purchases. Refunds are handled by Apple at reportaproblem.apple.com.
Your secrets never leave your device unless you turn on iCloud Sync or export a backup. See the Privacy Policy.