You should be using a password manager

Why use a password manager?

Password managers greatly improve your online security by allowing you to create a different password for every individual account you have on the internet. This ensures that if any one password is ever compromised, all your other accounts will remain secure.
Additionally, password managers allow you to create complex (and thus secure) passwords that humans would find very hard to remember.
They take the burden of remembering things, which we humans are bad at, off of our shoulders and let the computer handle that.

I would personally recommend Bitwarden as they are an Open-source company with known good intentions as they have been audited multiple times by third-party sources.
On top of this they have an extensive free tier with many useful features.