@Brian-McG on my helmet using a headset I can change these using the supplied app. In the car, adjusting the volume adjusts directions and music together. But trying to change volume of next app on phone keeps springing it back, but only when connected to car. If I disconnect, the app works as it should. The issue is that next app forces car to treat Bluetooth source as music. Google and other nav apps on the phone send their instructions as voice. So that’s a bug and an irritation to me as I can’t connect my phone and accept incoming calls at the same time (unlike in other apps)