I keep meaning to start using a password manager. I think that's really smart, and it ensures you have unique, difficult to figure out passwords.

Right now, I have a secret, password-protected file where I keep passwords, which is definitely not ideal. But I can't remember all of them, and I tend to pick really weird/hard combinations that are impossible to keep straight.

Plus, I use it to keep notes - like if it's a password to something that will renew/expire in a year, I can jot down the date.

But, yes! You should definitely have a different password for everything you log in to! If you don't, and any one of those sites/apps gets hacked... the first thing the hackers will do is take your email or user ID and password, and try it on a bunch of other sites, to see what they can gain access to.