Storing Passwords in Tor Browser
You may have noticed that the "Remember Password" option in Tor Browser is not available, or so it seems. But if you look at the privacy setting and alter the history setting to "remember history" and "remember passwords for sites," it will no longer be greyed out.
Diceware
If you must store passwords, a good option for a unique random one is Diceware - where you can get an expire date for any password months from the date of creation. You can copy any password to a text file then encrypt it and mail it to yourself or place on a removable (encrypted) drive or USB stick.
Remember: Tor does nothing to improve the security of your *system* to everyday attacks. It only improves security online, and even then only when used responsibly. Tor has no idea if your version of Windows is unpatched and infected with a zero-day malware payload that infected it with a keylogger.
One way in which a hacker could guess your complex password is if they linked your Tor usage with non-Tor usage and compromised your passwords from a non-Tor site. This is why you should never use the same usernames/passwords for Tor that you do for non-Tor activity.
