What if you also have an older Mac or iPad that can’t be upgraded that far? Here’s the trick: when you’re prompted for your password, type it and press Return to trigger the authentication request. However, those two-factor authentication dialogs appear only on Apple gear running iOS 9 or later or OS X 10.11 El Capitan or later. With two-factor authentication, when you log in to iCloud or iTunes for the first time on a new device, it prompts you for both your password and a 6-digit verification code that’s displayed on another of your Apple devices. Apple is increasingly encouraging us all to turn on two-factor authentication for our Apple IDs because it adds an extra layer of security on top of the password.
