A password manager helps you generate long, safe, passwords. Then it saves them for you and can automatically fill them in for you. A good password manager integrates with your browser, phone, desktop computer etc. They're available everywhere.
I use Bitwarden. It's free. https://bitwarden.com/
You can register here https://vault.bitwarden.com/#/register
The only password you'll need to remember once you start using it regularly is your master vault password for the password manager itself. If you can memorize it that's ideal. I use a series of 5 random words with spaces. The entropy of such a password should be quite large and thus a strong, fairly easy to remember, password. https://xkcd.com/936/
Once you're registered install it on all the things!
This is the downloader page https://bitwarden.com/download/
On Linux it's just in the app store for most distros
Android and iPhone it should also just be in the app store.https://apps.apple.com/us/app/bitwarden-password-manager/id1137397744
So it can auto-fill your passwords in your browser you would need to install
Chrome/Edge/Brave etc https://chrome.google.com/webstore/detail/bitwarden-free-password-m/nngceckbapebfimnlniiiahkandclblb
Finally, here's Bitwardens tutorial video for using the password manager. https://youtu.be/sf8qa2HcKSs?t=66
There are plenty more tutorials and guides out there on the internet available with a search.
Enjoy your auto-filled, strong, passwords!