In the first place…

…1.5 Billion is a pretty big number (except when you’re talking about the Federal budget, of course). So it’s eye-opening that, according to this article in Infosecurity magazine, there are 1.5 Billion username-password pairs from breached databases available on the dark net—and it’s even more eye-opening that some 60% of that number are re-used pairs, combinations used at more than one site. This represents a serious security risk due to that practice known as credential stuffing, sequentially trying known pairs in an atack on some valuable site.
 
Use strong passwords on every account you have, and never the same one twice.
 
You will never remember them all, which means you will have to write them down or, better yet, use a password manager (my favorite is 1Password, but there are many others). A password manager will also generate strong, random passwords for you, saving time and brain fatigue.
 
And while you’re at it, enable two factor authentication (2FA) on every account that offers it. 2FA requires a second token, in addition to a password, for access, and greatly improves security of that account.
 
Be safe out there.