if you want to make users logout every 1 hour, you have to set a session lifetime. This is based on your homepage.
Right ABOVE session_start(); in your core file, add following
PHP:
// server should keep session data for AT LEAST 1 hour
ini_set('session.gc_maxlifetime', 3600);
// each client should remember their session id for EXACTLY 1 hour
session_set_cookie_params(3600);