A password manager makes remembering all your passwords easier because trying to remember all your different passwords is hard. A password manager secures all of your passwords behind a master password so without that one password no one can get to the rest.
If one password is stolen only that one account can be compromised if all of your other passwords are different.
Sharing logins makes it easier for one to be stolen because there are more opportunities when there are more of you. If you do need to share a password for a business purpose use a password manager with business team features to securely share them with permission restrictions & auditing.
How easy is it to find out the answer to common security questions like your mother's maiden name? Treat security questions as just another password to stop them being used to gain access to your account by a malicious party
Make it that to log in you don't just need a password, you also need something physical like your phone. Using 2FA/MFA really boosts the security of your account by making it harder to access for anyone that isn't you.
If you are using a password manger you can generate random passwords which are much less likely to be guess than something simple such as a pet or football team. A simple password can be more quickly cracked or extracted through social engineering, and if all your passwords follow a pattern this could be exploited to get into your other accounts.