Clearinc console at log off

Hi When using console 2 to 6, the screen clears when I log out and the login prompt appears at the top. On console 1, however, the screen contents from the session remains (surely this could be a security issue?) So, what setting / config file do I need to attack to get the clear-screan function on console 1? Also, what command would clear the screen from the command line during a session? Cheers Dylan