About setting the password
Locking your notes keeps them private from others who might use your Mac, iOS device or iPadOS device. Notes uses a password to lock the notes you choose — both notes in iCloud accounts and notes stored on your device. If you enabled the option, you can access your notes from a device that supports Touch ID or Face ID, then use either method to open your private notes.
Important considerations when setting the password:
If you enable Touch ID or Face ID for both your device and Notes, anyone with your device’s passcode may be able to access your locked notes.
If you have both an On My Mac account and an iCloud account, you can choose whether to use a custom password or your login password for either account. You can switch between using a custom password and using your login password in System Settings.
If you forget your password, you can view a locked note by using Touch ID or Face ID (if you have a device that supports one of those features and you enabled it before you forgot your password). It’s strongly recommended that you add a hint when you create a custom password. Notes shows the hint after two failed attempts. Additionally, you are required to re-enter the password if you update your Touch ID or Face ID settings.
To change a custom password, you must know the current password (unless you have Touch ID enabled).
When you create a custom password for the notes on one device, all other devices that use the same iCloud account use that password, too.
If you use your login password to unlock your notes and you enable Touch ID, you’re not required to enter your password periodically.
If you use your login password to manage locked notes and your notes are synced to another device, you will unlock those notes using that device’s passcode or login password. Other devices must be using iOS 16 or macOS Ventura to see notes locked using your login password.
Locked notes are only visible on devices with OS X 10.11.4 or later, iOS 9.3 or later or iPadOS 13 or later; on devices with an earlier OS, you won’t see the notes at all.
To learn more, see Lock your notes.