I was shooting in the dark a bit with my last reply, since you gave so little information! It seems you have Android Auto set up correctly.
Android Auto and Apple CarPlay allow you to 'project' your phone onto the center display and use the touchscreen, car speakers and microphone with the phone applications. They don't let you control inbuilt car functions like changing the infotainment system audio sources. If you want to use Google maps for navigation, then you go to the Android Auto display on the center screen and hit the Google maps icon (assuming you have it loaded on your phone). You can then run the app from the center screen just as if you were running it from your phone. If you want to use the Volt internal navigation system instead (assuming you have that option) then you hit the navigation icon on the 'home' center screen display. Of course, the Google maps phone application will not be able to lower the music sound level when voicing navigation information, nor give a direction graphic in the driver instrument display behind the wheel, as the inbuilt navigation system can.
As for using the steering wheel mic button with your phone connected, a short push on the button should bring up the Volt internal voice command system, while a longer push will bring up the phone voice system (Siri in my case, since I use an iPhone). Once I've chosen which system to initiate, I've never had any conflict been the Volt internal voice commands and the Siri commands.
As for remotely starting your Premier, did you download the Onstar mobile application? You can download it from the Google Play store in your case. Once that is set up, you can remotely start your Volt using that application, and use many other features.
Hope I did a better job of answering your questions this time!