I strongly recommend using a Password Manager. There are many out there to choose from, some free, some at a cost. Optimally, I look for a Password manager to remember my passwords and usernames, generate complex, random passwords and I can access on whatever operating system I use, from Windows PC, to Android Tablet to iPhone. And if it's in the cloud, I want it to offer two factor authentication. I also want it to update itself when I do change passwords.
There are different types of password managers. Some keep an encrypted file on your computer, others have your passwords encrypted in the cloud. The latter means you can use it from any device. And you can use them for more than password managers. Since they are encrypted, you can store other bits of information there that you want to keep safe, such as insurance cards, drivers license, etc.
I included some information about Norton and LastPass. If you have Xfinity/Comcast for an ISP, you have access to Norton. And if you are using an Apple (Mac, iPhone, iPad, iPod Touch), you have access to iCloud Keychain.
I also recommend that you sign up for a notification service, Have I Been Pwned (HIBP). It was created and maintained by Troy Hunt, a Microsoft Regional Director and Most Valuable Professional awardee for Developer Security, blogger at troyhunt.com, international speaker on web security and the author of many top-rating security courses. Here is an example of what type of notification you would receive if your email address was found in a breach. This happened in January 2019.