password change

I tried to log in to blog stats and it kept telling me that my password was invalid. I finally just asked for a password reset and was able to log in with the new password. I would now like to change my password back to my original password, but it doesn’t seem to accept the change. Is this because WP won’t let you change back to password you used before, or am I doing something wrong?

It also doesn’t seem to “remember me” when I check that box.