Songpal and Sony N5100BT

[KMS]

I bought this in order to throw into the glovebox and put an ipad in the dash. However I'm having a bit of a problem and not sure if it's just me or the unit. I cannot open songpal from the ipad to change settings without having to manually go into the glovebox and set the headunit to bluetooth on the source. Is there anyway I can leave the unit playing spotify via usb and open spotify while still playing spotify music and change the subwoofer level through songpal? Or do I have to go into the glovebox every time and switch sources between usb and bluetooth whenever I need to change subwoofer level? I could use a subwoofer gain knob but would like to just bypass it if I can.