I wouldn't say this to be a very secure method. I agree with @grizgal, use a password manager. i have a free app on my iPhone an app call called ipassword. It requires you to use your fingerprint to login. As a back up, I have taken a screen shot and saved that into a secure folder that only I have access too. I would be very surprised if anyone knew what it was related to if they did stumble across it...unless they work for MI5 or Mossad, then i'm screwed!