Cookies and HTTP Header Options 
The vBulletin Options > vBulletin Options > Cookies and HTTP Header Options setting group allows you to control the cookie settings, gzip compression, HTTP headers and redirect messages options.When you are done, click the [Save] button to apply the changes.

fury 20th Apr 2005, 11:03am
Timeout for Cookie option - this setting essentially changes the length that a vBulletin session stays alive, so if you change this setting, be aware that your Currently Active Users display will change accordingly. For example, if you change the timeout to 3 hours, users who have visited your board within the last 3 hours will be displayed in Currently Active Users areas (forum home page, who's online page, forum display page, and show thread page).