How to get iTunes to play hd movies and music with Dolby digital 5.1 support on windows 10?

I have windows 10 PC with iTunes 12.5.1.21

i want get iTunes to recognize the Dolby digital 5.1 speakers that I have and use that to play the sound from the movies and music. Currently it looks like I only get stereo sound only.

WIndows 10 operating system does recognize the 5.1. I checked this by using testing feature in the control panel >> sound >> manage audio devices and selecting the 5.1 speaker system.

I'm playing the hd movies and music that I purchased in iTunes Store. Is it that the HD movies in iTunes store don't support Dolby digital 5.1? Or am I not doing something right in the settings?

PC configuration and setup:

• Dell Alienware R2
• 16 GB RAM
• nvidia GeForce 960m 2GB RAM
• USB external soundcard - Creative Sound Blaster Omni 5.1
• optical output from the sound card connecting to BoseSoundtouch 520
• HDMI from the PC connecting to a projector LG PF1500