If you’re struggling to keep your online accounts secured with unique alphanumeric passwords, it might be worth looking into a password manager, like the excellent LastPass and 1Password.
Both of these options store all of your online logins in an online vault, which is locked away behind a single password – or your fingerprint, or Face ID scan when using a smartphone to unlock the account. This means you don’t have to remember each username-password combination.
As such, you can use randomly-generated alphanumeric passwords for each online account. And when you need to login, unlock LastPass or 1Password with the single password you remember, and then the app does the rest – inputting a 20-character jumble of symbols, numbers and letters into the password field in the app or website.