the better way is probably to store this particular sensible password on a piece of paper , stored in a safe place.
I also like this old idea. I actually have a little notebook which I keep somewhere but I just make sure that nobody can access it. Anyway, there are only two of us in my house and I am sure the other one does not know anything about the computer so I am 99% safe...except maybe if there can be a fire that can happen in my neighborhood then it can be a challenge lol. Having a good copy of our passwords is a good idea.
You could get a small fire safe and store it in there in case a fire were to occur. You'd probably also want to store it in a water proof bag or something to prevent possible water damage.