1.  Press the ASSIGN push-button and hold it down.
2.  Activate the control element, for which another channel than the GLOBAL CHANNEL is to be set.  If this is a controller or fader, briefly move the control element; when you have decided on a push-button, press the push-button once.  The UMX now "knows" to which control element you would like to assign a SINGLE CHANNEL. 
3.  Release the ASSIGN push-button. 
4.  Press one of the 16 channel keys "CH 1" through "CH 16". 
5.  Finally, press the ENTER key.  In order to discard your assignments, please select the CANCEL key or press the ASSIGN push-button again.  The ASSIGN LED will go off in all 3 cases.