How can i get my jvc stereo to sort files by artist instead of album?

My KD-R520 JVC stereo receiver only sorts the wma's on my usb by album. I have 67 albums on one usb, but they are grouped alphabetically by album name, not by artist name, even though each album is a subfolder of the artist folder. Is there any way to make it alphabetically by artist, then album? I've looked at the manual and there is nothing I can change in the settings. Maybe if I renamed each song by artist, then song title? I can't bring myself to do that, Its tedious and ridiculous.