I had the same problem when I first tried out my car with a USB-A Flash drive and the Sales doesn't know why either so I just left it with them since I won't pick the car up till the next day and they later sent me a video showing me how to switch.Duh, what an idiot! I didn't see that.How embarrassing. I'll see later.
My excuse is I picked the car up yesterday after the dealer got the screen working for the 1st time, a pinched/broken wire in the dash. Though the reversing camera isn't working either.
Thanks for that.