After some research on line, including opening a topic at Games4TheWorld for help among other things, I found very useful information (and sites) that would calm me down and help me set up a strategy.
Without spending any money, you can visit a couple of websites like Have I Been Pwned? or Firefox Monitor and provide them with your email address(es), that way you will find out which leaks affected you, if any, and also show which information was compromised in those leaks.
It’s always advisable to replace your passwords once in a while, but who has the time to go to thousands of websites, replacing them one by one?
Plus, if you don’t use a password manager like KeePas (not sponsored by them or anybody else) or your browser built in tools, how can you remember even where you have created all your user accounts for the past year, or perhaps a decade or two??? 😲
Well, it’s hard work, and it will take you hours, days, for sure, unless you’re a very organized person. There’s no way around it, you need to replace all your important passwords (at least) with new ones, one by one 🤦🏻♂️. It’s impossible to just create and memorize one different password for each service, unless you use some sort of formula or if you have a fantastic memory!