Click on the Start button, then click on "Run...", Then in the box type
An explorer window will open and it might even open to the correct folder of settings if not then navigate to the following path
From there you should see the setting for
HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\ Terminal Server\WinStations\RDP-Tcp
Double click on it and then change the radio button to Decimal and change to the port that you want it to exist on.