Keep Your Notes Private By Locking Them
You can use the Notes app for pretty much anything, whether that’s writing a to-do list or jotting down your most personal thoughts. However, you probably won’t want anyone snooping around and finding your private notes.
Fortunately, there’s a simple way to keep your notes safe: lock them. When you lock them, you’ll only be able to open them if you enter your Mac’s password or if you use Touch ID.
To lock your notes, select the note you want to keep private, click the Lock icon at the top right corner of the Notes window, and then select Lock Note.
Next, enter your Mac’s password. Now, you’ll see a small lock icon on the left side of the note, but it’ll still be open. Don’t worry; all you need to do is click the Lock icon in the top right corner again and select Close All Locked Notes. If you close the Notes app, your note will be automatically locked, too.
It’s worth mentioning that you can’t lock all notes. For instance, notes with a Tag can’t be locked. You’ll need to remove the tag first.