To change the damper associated to a zone, you first have to reset that zone. To do so, access the Zone settings menu and then access the Reset thermostat parameter. Select Yes and the thermostat will be set up with its default factory settings (see the section entitled Zone Advanced Settings in the Installation Manual).

Now you only have to associate the new thermostat and choose the desired zone. To do so, follow the instructions in the System Initial Settings section in the Installation Manual.