My wife and I know one another's passwords, PIN numbers, etc. So in the event of one of us dying before the other, we can access all the relevant computer, etc

My wife and I know one another's passwords, PIN numbers, etc. So in the event of one of us dying before the other, we can access all the relevant computer, etc stuff. Other than that, wills, PoA, etc take care of the legal stuff. Records of passwords, etc are useless if you change them on a regular basis. How can you be sure that you update the paper records?