Setting chat room timeout globably

Total newb to IM Servers in general and Openfire/Spark in particular. I am evaluating IM for use in our operations group so that people can all be aware of daily issues as they arise. Have installed Openfire and Spark for a few users and created a Chat Room for the daily thread. I want to set a long timeout for the chat room so people are alerted throughout the day even if there are long periods of idle time. Can I set this parameter globaly or do I have to set it for each client when installed?

PS: Thanks to all those forum members at Openfire who addressed issues re configuring Windows Server AD. With a few searches and a little tweaking I got Openfire working with AD in about an hour.

Are you talking about Idle User Settings in the Conference service settings in the Group Chat in Admin Console? Then this setting is global for all rooms on that service.