Chapter 23 WAN Optimization, Web Cache, Explicit Proxy, and WCCP : Web caching and SSL offloading : Changing web cache settings
  
Changing web cache settings
In most cases, the default settings for the WAN optimization web cache are acceptable. However, you may want to change them to improve performance or optimize the cache for your configuration. To change these settings, go to WAN Opt. & Cache > Cache > Settings.
From the FortiGate CLI, you can use the config wanopt webcache command to change these WAN optimization web cache settings.
 
For more information about many of these web cache settings, see RFC 2616.