Have not had any experience on this radio, but I am sure if you save your current codeplug you can play with the tones and see how you get on, if you screw up you can re-load your saved codeplug.
I have a copy of the Hytera 785 CPS and yes you can change both the tones volume and the tones composition, just remember they sound different on the computer from the radio..
Connect Systems CS750 and CS800, Hytera PD-365, Motorola DP4600
Raspberry Pi 2 and DV4Mini HotSpot
AOR AR-DV1 Digital Voice Receiver / eSPYonARD
WS1088 / TRX-1 / Whistler Q / UBCD3600XLT