USB Song file play order

[Honva]

I have the 2012 bose audio with gps. The manual said the play order of song files in usb is determined not by alphabetical order but by order the files was written. However, even though I copy the files one by one, the head unit does not play back in that order (also not alphabetical order) (and Random is not on). Any one know how the head unit actually decide the order?

Thanks.