>>A password keeper is what keeps me sane
Although there are many keeper apps, I use 1password to store all my usernames, passwords, except bank* logins, and password-related notes. Although I only have the iOS version, I can access the info on both our iPhones and iPad and I almost always have my mobile close to hand. When I create a new account, whether on iOS or Windows Firefox, it goes straight into 1Password as I have lost too many sticky notes, etc. or simply forgotten over the years.
The other important point, for me, is that others, e.g. my wife and daughter, have a central point for access should I become 'incapacitated'. Most of the passwords are not really all that important, but utilities, NAS access, emails, Apple ID, to give a few examples, are possibly important.
* not storing bank info is not against my wife or daughter accessing it, but the banks insist that you do not write your password down or share it. They must think that we have incredible memories... If someone got into my iPhone and then 1Password followed by emptying my account, the banks would deny all responsibility. So I have to remember 1£$UnM7&*_-#~klPu (or something non-similar)