How do you adjust the volume on nav directions on Google Maps? It say to adjust it using the car’s volume control while nav instructions are being given but that doesn’t seem to work. Help!?

 

so after considerable 'futzing around', including calling Lexus, I find that WAZE has a volume control within the iphone app that successfully adjusts navigation prompt volume although Google Maps has 3 choices within the app, ie, LOUDEST MEDIUM and SOFTEST but there is no discernible difference when the prompts actually play. I guess WAZE is the go-to nav app.