I have used a couple of different USB thumb drives in my 2012 Terrain because I got a drive with a much smaller form factor. I have also used an iPod Touch to host music. The problem I now have is that the stereo apparently keeps its own index of play lists, albums, etc. so I have many copies of almost every kind of list to wade through. Does anybody have any idea how to clear all play list, albums, etc. and force a re-index?