A locked note is useful only if you can reopen it when needed and close it when finished. Before moving valuable information into one, test the lock with harmless text in the same Notes account and on the devices you expect to use.

Apple supports locking notes stored in iCloud or On My Mac. In Notes settings, select the intended account and choose a supported password method. A custom Notes password and the Mac login-password method have different recovery and compatibility implications.

Confirm eligibility and access

For the login-password method, Apple specifies iCloud two-factor authentication and iCloud Keychain when using an iCloud account. Other devices need iOS 16 or macOS 13 or later to view notes locked this way. Check an older device before assuming the note will remain usable there.

Create a harmless note, use the Lock Note command and then close the locked notes. Reopen it using the chosen method. Repeat on each device required for the workflow, using the correct account.

If Lock Note is unavailable, inspect the note’s contents and type. Apple excludes shared notes, tagged notes and certain attachments, including PDFs and document files. Do not remove useful content from the only copy merely to make the command available.

Check the unlocked session boundary

Unlocking a note unlocks the other locked notes in that account for the session. Use the lock control to close all locked notes when finished, and verify that the contents are hidden again before leaving the Mac or sharing its screen.

For a custom password, preserve a reliable way to remember it. Apple warns that it cannot recover access if that password is forgotten and Touch ID cannot unlock the notes. A successful biometric test today does not replace knowing the password.

Once the harmless test works, decide whether Notes meets the actual requirement. A project needing collaborative editing or ordinary document attachments may need a different storage method. Keep the information in its current safe location until the chosen workflow has passed the access and closing tests.

References: Apple: locking Notes on Mac.