I couldn't find this setting anywhere in Android settings. The resume on Start is not checked. I also don't have Poweramp set as default player, so I don't think it's an Android issue...
I am using Poweramp version 2.0.10-build-588-play (Full Version) on Samsung Galaxy tab S3 running Android V7 . My problem is that despite unchecking "Resume On Wired Headset" checkbox, when I insert the headset plug, the player turns on and the music starts playing. Interestingly enough, it doesn't do it all the time. Anyone else is having this issue?