How to Change Session Timeout/Session Timeout Warning Time
An option exists to establish the length (in minutes) of either Session Timeout or Session Timeout Warning Time for the application. The Session Timeout indicates when the user will be automatically logged off from the application and Session Timeout Warning Time indicates when the user will be warned prior to being logged off from the application.
1) From the Administration icon in the navigation menu, select Settings and then Preferences Administration.
2) Under Security select Session Timeout or Session Timeout Warning Time.
3) First, select the Scope for which the changes will be performed (Domain versus a specific Organizational Unit).
4) Then indicate (in minutes) the new Session Timeout or Session Timeout Warning Time.
AND/OR 
5) Click on the Save button to save the setting(s).