I have a 2018 Model S. I like to keep the Navigation voice at the lowest setting possible. Whenever I'm listening to an audio source, whether radio, Tune-in or other, if I increase the volume while the Nav voice happens to be providing a command, the Nav volume is also raised. I then have to press the "settings" gear wheel on Nav to reset the voice assist to its lowest level ONCE AGAIN! Hrumpf! Can't a "Save" feature be added for this?