Mic Gain Setting Not Working in HD1?

I bought a new HD1 and the first thing I tried (after program it :-) ) was to adjust the Mic Gain, I need to lower the Tx mic level in DMR and for some reason I changed the values from -10 to +10 and there is no difference. How can I adjust the Tx mic level ? I tried setting it in the radio and then with the CPS same results, NO change.