When the sat nav is in use and she is speaking use the volume control to turn it up. You can also go into the settings menu and do it from there.
You have to have the unit on so the only way to use the nav without the radio is just turn the radio down till it shows audio mute at the top of the screen
You have to have the unit on so the only way to use the nav without the radio is just turn the radio down till it shows audio mute at the top of the screen