Okay. Lots of us are reusing passwords. Lots of very bright, educated, and conservative people do this. THIS IS A TERRIBLE IDEA. Please read this article from Wired Magazine. It explains the whys, the wherefores, and offers some good options for moving forward. Even if you are not quite ready to take action, you will come away with a much better understanding of the big picture. Here is the link:
Apple's integrated password management features are part of both MacOS and iOS (for computers and mobile devices respectively). You can not only autogenerate unique secure passwords and look them up easily, but also synchronize updated passwords across all your devices using iCloud Keychain. This is what I use for the most part, even though I do not use Apple's Safari web browser exclusively. Once you know your way around it works pretty well in most instances. I've yet to find a tutorial that is good enough to link to here. Yet. I'll keep you posted. The trouble is the technology evolves rapidly and varies according to your hardware and software version, so it is not one size fits all. You can get get the currect overview of iCloud Keychain here.