General System Administration -> Keystone - Only -> Keystone Client Parameters (KZ0050) -> In the Autologout field enter the amount, in minutes, that you want to allow for a user to be inactive before automatically logging them off
System Administration Menu -> KEMS Parameters -> KEMS KeyNet Parameters (KE0715) -> Security Parameters (KE0626) -> Enter the amount, in minutes, for the KeyNet Session Timeout and Warning before Timeout fields