I just use NotePad text files (hundreds of them), stored in an external drive folder and several flashdrives. If you find a good app, share it, please!
Rather than using Notepad text files, try
PINs Secure Passwords Manager.
I've been using it for years. One password to all your other passwords, phone numbers, credit card numbers, etc.
It is small, light, simple and will run from a hard drive or thumb drive. The thumb drive is best as it is most portable but keep a backup on your PC in case you lose the thumb drive.