I'm just chiming in to say I have the same issue. I don't use android auto, but still tried the fix earlier in the thread. All my audio focus settings are off, no auto starting enabled. I drive multiple short distances with clients in the car, and man is it embarrassing when Poweramp starts playing my music even if I wasn't listening to music last time in the car. Or if I start using my earbuds to finish watching a video on yt and Poweramp aggressively takes over. I understand Poweramp is acting "correctly" yet this is still an issue. No other music app behaves this way. I've been using Poweramp for years (paid) but I had to uninstall to keep my sanity.
