DJM900 NXS USB sound card inputs

1. What software are you using?  
2. What exactly are you trying to accomplish?
3. Are you on a Mac or PC?
4. Which operating system do you have installed?
5. Have you upgraded to the latest firmware?
6. Have you installed the latest proper drivers?
7. Do you have all the input select knobs set to USB? (red arrows)

doesn't matter what the software.

tried a lot on both PC and mac on both USB A & B doesn't matter still its only on channel 1.

to confirm its the DJM900 NXS2 with latest firmware 

USB A and B are built in sound cards (at least thats what i thought) but for some reason you can only play back on channel 1a or channel 1b

none of the other channels seem to work on the USB input 

the screen shot above is not the DJM NXS2

@Rich21 > The screenshot is a DJM-900nexus since the title of the thread says "DJM900 NXS" not NXS2.  I can assure you that the mixer isn't broken, so in order to figure out what you're doing wrong I will need you to provide answers to all my questions above, disregarding number 7.  The only ones you've answered are 3 and 5.  

1. What software are you using?  Every software has different settings for different hardware
2. What exactly are you trying to accomplish?  For example, If you're trying to use DVS, you're wasting your time as the mixer doesn't currently support it.
3. ------------
4. Which operating system do you have installed?  This will help us learn which driver(s) you should install and about some additional settings that may be applicable.
5. ------------
6. Have you installed the latest proper drivers?  Without the proper driver(s), the mixer won't work with your computer(s).

software: rekordbox (internal player) and default music player and (audacity on the pc)

OS: window10 and mac osx 10.10.5

all programs on both OS will play back via the USB sockets A or B but audio will only work on channel 1A or channel 1B 

latest firmware and i have double checked the drivers on both mac and pc

ok think i know whats going on now.

each of the builtin sound cards are multi channel (10)

all the software i have tried defaulted to USB channel 1&2 witch only work on mixer channel 1

when i changed this setting to USB channel 3&4 the audio worked on mixer channel 2 and so on

thanks for your help