One of the most common problems we encounter several times a day is the repeated use of the same, often weak, password closely followed by "I've forgotten it" and frequently followed by assorted curses.
These days, most systems have some way of storing these passwords, either within the core of the system, i.e., Apple iCloud, or in the web browser itself.
If you are reluctant to save the passwords on your device and you don't have a great memory then it's worth investing in a small address book and recording the information using the alphabetised pages, e.g., Hotmail details would be found on the H page. Get used to writing the password in pencil and recording the date alongside so that you know when it was last "correct". Using a pencil rather than a pen allows you to erase it when it needs to be changed rather than lots of crossed out passwords filling the page.
Another option is to use a password manager so all you need to remember is one strong password to unlock the application and have synchronised access to all of your stored passwords on all of your devices.
Many security packages now include some form of password manager but if you would prefer a stand-alone version then these are worth considering:
Bitwarden - https://bitwarden.com
LastPass - https://www.lastpass.com
1Password - https://1password.com
Should you decide to store your passwords in your web browsers then it's worth checking them periodically as the browsers nowadays will often highlight weak, reused and compromised passwords.
To increase the strength of your passwords try to make them at least ten characters long, break up words by randomly capitalising one or more letters, pop in a number and use special characters such as @!&$*#~
Avoid using pet or family names as they are often easy to find or guess.
If you ever feel the need to see if your email address has appeared in a data breach then take a look at https://haveibeenpwned.com
You may be surprised by the results.
Sleep well.