I'm using Poweramp (paid version) on a Nexus 5 and a lot of my "Thumb" art in album view (grid or list) is incorrect. I tried to follow your steps to change it, but no such luck. I can get the HQ art in Player view mostly good (based on the images that are returned when searched - not always perfect), but why doesn't that overwrite the folder images? I'm still stuck with incorrect images on most albums. To rectify this, I downloaded Album Art Grabber from the Google Play Store and used it to acquire all the correct images. They appear fine when I use Google Play Music, but I'd rather use Poweramp, and those images won't appear, even after clearing the data through Settings->Apps on my phone. This seems like an incredibly basic thing, but it's driving me nuts! If I can get it to work with the free music app that came with my phone, why won't it work on Poweramp? Please help!