In the Notes app .
Tap Lock.
When a note is locked, the title remains visible in the notes list.
To remove a lock from a note, tap , then tap Remove.
Opening one locked note opens all your locked notes in the same account for several minutes so you can easily jump into another note or copy and paste information from other apps.
Tap the locked note, then tap View Note.
To open the note, use your Notes password.
To lock your notes again, do one of the following:
Tap the lock icon at the top of the screen.
Tap Lock Now at the bottom of the notes list.
Close the Notes app.
Lock your iPod touch.