Hi Andre,
No I think there is a confusion let me try explain the details
I have Poweramp installed on my phone and on my headunit. I don't use Poweramp from my phone via BT on my headunit. I only use the Poweramp installed on my headunit as I have all my media already stored in my headunit, so I actually rarely use Poweramp on my phone it's just installed there if I need to listen directly on my phone (away from my headunit I mean) so I think we can take Poweramp installed on my phone completely out of the picture.
Now, when I ride my car, I activate BT on my phone only for the sake of taking my calls on the headunit, and not to stream Poweramp from my phone by BT to the headunit. Now, when I turn on my headunit, the Poweramp installed on my headunit directly opens in full screen although without playing anything, it's ready just for pressing play on whatever track it's open on.. I hope I was able to explain.
So in this case, would the above setting still help? and would it affect anything else? I could also try it once I'm back in the car again and let you know.