Finally, I think I am done fighting with my PX6.
I joined a FB group ( I think it was linked here a few pages back, when another member posted a photo of their screen without a bottom menu bar) and the admin is a man named Sergey Kozlov. He makes his own firmware for the Tesla-style radios. After installing his custom firmware (which allows for things like making the top and bottom bars go away), it fixed my audio switching issues when going from SYNC 3 to apps on the tablet. Then, we tackled my steering wheel controls.
I noticed the other day when I got in my truck, that the home screen on SYNC 3 was open and said "Audio Off' in the top-right corner. Keep in mind I have had a Tesla-style screen in my truck since day #2 of owning it, so seeing that "Audio Off" was a new thing. I forgot that I used to have a power button in the center of the volume knob. With that in mind, I tried launching Amazon Music without turning on any audio in SYNC 3, and after Amazon Music was playing, I was able to use my steering wheel controls 100% no issue. The following day when Console opened, it was on my first preset, and I tried it again, and it was back to the old issue of steering wheel controls chaning both the app track, and Sync 3 presets at the same time, but only hearing SYNC audio.
With all of this information in mind, I contacted Sergey and presented it to him. He made me an update, that replaced the "Media" button in my Console app, with a "Power" button, so I can turn off SYNC audio and use my wheel controls.