A:Answer This is the way I added my sound bar: just fyi, I purchased a different brand than Samsung so this may not be completely accurate but I hope it helps you with your setup. After I plugged in and turned on my sound bar and connected the subwoofer to it via Bluetooth, I plugged the fiber optic cable in connecting it from the sound bar to the TV. This next part is where I think you are stuck...
With the TV remote, go to menu, then scroll down to sound and select that option. Then there should be a few options for sound: the TV speakers, Bluetooth, and Optic (fiber optic). Scroll down to optic/fiber optic and push select. That should do it!
Hope that helped