Currently, when the user is loggged out, on user login form, the username field is filled with text, which probably is taken from a cookie (not sure) - it is the name of someone who logged in before. The password is also filled with dots, representing previously logged in password.
How to prevent it, i.e. always display username and password fields empty?
P.S. Why I need this? Because the requirement is that in the user name box there is a placeholder behavior with text "Username". (HTML5 placeholder). I noticed that it works well when the browser has no username remembered and does not work at all when the browser remembers the username and password.