We can't remember our passwords.And neither can you, be honest.
Too many accounts
Where possible, I recommend to sign in with a third party like Google, Facebook etc. These are called Single Sign-On (SSO) and they let you use an existing account to verify who you are.
Keep your eyes peeled for these buttons
This will save you from adding a new account to you password book, and is generally considered more secure by those in the industry. It’s likely that your Single sign-on has the option for two factor or two step authentication, but not all websites do.
As a company, we use KeePassXC. A simple password manager which works on Windows, Mac and Linux.
This is an offline, 256-bit encrypted password safe. If you need to access you file on a phone or tablet you have the option to throw a copy on Google Drive or iCloud.
They seem daunting to setup, but once you take the plunge you won’t be reaching for the password book again!