How to change radio control keys

Hi just woundering if anybody knows how to change the FS2004 radio keys. I have bild a FS consol and my default keys to respond to the control tower are o,n,h,p,z,s,0,9,6,5 I tryed to change under key assignements but it's not there I gess it's programmed in right now as you all know to respond to the radio tower are 0,1,2,3,4,5,6,7,8,9 I need to change them to work with my consol when radio says press 1 for take off clerance I can press my switch witch is n