Basically, keeping my crypto assets is way more than secure than keeping my fiat money. Writing account information in a paper is not also necessary because it's too risky and will just expose your digital assets to someone else if you lost that piece of paper. Even saving my account's information on e-mail is too risky so i just keep it on an external drive and keep it somewhere only i know.
I hope you've got all that saved on more than on external drive, as they're known to fail and you dont want one single point of failure to throw a wrench in your life!