A proven strategy to manage passwords, PINs and other sensitive information is to use a password manager application.
There are paid, free and open source solutions, in the cloud or local, that guarantee the best possible usability based
on powerful military grade encryption.
mdss most of us use
KeyPass. This application is open-source, free and available in any platform, (Windows, macOS, Linux, iOS, Android...).
Check these two articles that include detailed comparison data on the leading solutions:
PC Magazine and