Password protected page

Anyone, using the Generate Press theme and I need to password protect a particular page on a site. I attempted to set the visibility function while editing the page. That works to an extent, but I need the user's session to time out when they are done viewing that particular page. This is especially critical if the user is on a computer accessible by any number of users, an unauthorized person could simply pull up that particular page I am trying to keep hidden. Can anyone give me a hint where I can find session cookie settings in that theme

thanks
dave