please that im serious on this cause i had lost my first bitcoin wallet registered in 2010, i dont even remember what's the website address and i had a hard copy for that actually
How about using the old and traditional excel spreadsheet to write down everything and have multiple back up of it? Don't back up using emails though, because if you get hacked, most likely all your account is compromised. Don't back it up online, USB is a good option to back up.
I would also suggest that you write down it down if you are too paranoid to save in somewhere online or even back it up on a USB drive or any device. Again, you need to keep multiple backups and also put it somewhere secure so that no one can get to your notes.
And don't be this guys: https://cointelegraph.com/news/crypto-investor-reportedly-hacked-for-2-mln-on-live-stream-internet-calls-foul
He back it op in on Evernote, and the hacker was able to get his email password and the rest is history and millions worth of money is gone.