Fix for Steam not remembering password on Windows 10

If Steam keeps forgetting your password on Windows 10 even when you've checked the 'Remember my password' box, here's an easy solution.
steam-login

Exit Steam and navigate to your personal user AppData directory, usually under C:\Users\<Username>\AppData\Local\Steam.

In here you'll have two directories, htmlcache and widevine:
directory

Delete the htmlcache directory and then start Steam up again.

Once you enter your username and password check the 'Remember my password' box and log in.
remember-my-password

Steam should now remember your password, even after restarting your computer.