Watch notes stores all notes on your Apple Watch and a selected note in the widget. So you have everything well in sight.
Save as many notes in the app as you like and give each note a title so that you can more easily keep track. Your notes are stored in iCloud, so you can see your notes on all your devices and can there edit it.
Protect your app with touch ID (if youre using no touch ID, you can use just a password).