For me personally im just keeping my password on my small notes, fb ithink just is a one way to maintain r bitcoin safe or maybe uwant shop in equipment purses . always remember just keep it personal dont scatter passwords to anybody .
Facebook? you mean storing your passwords and private keys on Facebook? I don't think so man, what if someone hacks your Facebook and that someone knows about cryptocurrencies, steal your money, and when you check your wallet, it is all gone, I bet you are going to be annoyed because you saved it on your Facebook, that was a naïve way to store your bitcoins.
To keep it safe and sound, I suggest to use hardware wallet, because it is so hard to hack unless you are going to give it to someone personally or if you are just going to let your hardware wallet lying on anywhere around your house.