FileVault is a feature that encrypts the data on your Mac's startup disk, making it more secure. To unlock your Mac, you need to enter your account password or a recovery key. A recovery key is a 28-character code that is generated when you turn on FileVault. You can choose to store it in iCloud or write it down and keep it in a safe place. An iCloud account and password can also be used to reset your FileVault password, if you enabled this option when you turned on FileVault. The other options, authenticator app, using a trusted device, and SMS verification code, are not valid ways to reset a FileVault password on a Mac. References: 1 Use FileVault to encrypt the startup disk on your Mac - Apple Support 2 Reset a macOS User Password - Kandji 3 How to unlock your Mac with its Recovery Key and FileVault active - Macworld