Firfox Web Browser — Security?

There are a lot fans of Firefox, the web browser. And there are claims of better security. But, as a guest on a computer, even in the default configuration for Firefox, you need to be careful. If you use a secure log-in to view some private data and then log out, you will be surprised to find that your user name and password (in asterisks) is still there when you come back to the log in page. Hit the log-in button without typing anything and you (or anyone else!) get right back in to private data.

Quit Firefox and re-open and you still get right back in. Even a reboot of
the machine and you still get right back in.

The solution to clearing your user name and password? Go to
the Tools Menu and select ‘Clear Private Data …’

Only then will user name and password be cleared! That is NOT secure!