To change the time or location of a meeting, open up the meeting in Outlook by double clicking the event on your calendar, and make the required changes. Make sure to check the Scheduling tab before hitting send! If the room is already booked during your new time, it will reject the meeting.
Once you verify the room and needed resources (projector, etc.) are available, click send. It will send an update to everyone you invited and automatically update it on the meeting room calendar. That's it!