You wouldn't use the same key for your house and your car, right? So you shouldn't use the same password for all of the important online systems that you join.
But how do you choose a good password? How often should you change it? Is your current password strong enough? How can you tell?
All these questions, and more, are answered in a really useful article that you'll find at https://heimdalsecurity.com/blog/password-security-guide/
In addition to some great advice, there are also links to other useful sites that will help you keep your personal information safe. Definitely worth checking out.