Terminal server client resolution too high and need to be lower

I have a client using rdp session to a 2008 R2 terminal server. The resolution from the session status indicate it's at 2704x1050 while others people sessions are at 1680x1050 or 1024x768. My problem is I can't find the location where I can lower down that resolution. Can someone point me to the direction whether this setting is on the client computer or on the terminal server itself? Thanks.
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