Originally Posted by
SpookDroid From your phone, open the Android Auto for Phone Screens app (if you don't have it, get it from the Play Store). There, tap the menu button on the top left and select SETTINGS. In that screen, tap the "Hey Google" detection option and turn off the 'Hey Google' option. That way it will only be triggered with the screen or if your vehicle has support for a voice command button.
I want to again thank you for helping me solve this issue. Your suggestion was an obvious one but there's such a thicket of menus and apps, on the phone and in the car, that I missed that one. It's hard to prove the absence of something, but I WAS able to use my voice when I wanted to with Android Auto, but I had the radio on, and the assistant wasn't triggered, and I also tried saying "hey google" and "okay google" with the radio off, and it didn't jump in. Looks like it's fixed. Thanks again, a lot!