After I started using LastPass last month, I changed all of the old, weak passwords, and my security score became pretty high. Recently, however, the security score became lower, even though I didn't do anything. I ran a security challenge, and found out that LastPass had my old password back in the password field for one of the websites. When I click to show the password history, it clearly showed both the old and the new passwords. I can't launch to the website from LastPass, indicating LastPass is indeed using my old password for the site now.