Ideally, you want to use long, strong and unique password for each of your on-line account. The issue is how to remember them all. For that, you can use a password manager that will remember all your credentials in one place. Such a piece of software should also encrypt your database (password repository) and should beable to generate long random passwords.
You can then afford to only remember one password. Make it long and complicated, and above all, don’t forget it.
If you are using any other, let us know which one and why you chose it.