Magnifi Max SR - unable to achieve Dolby Digital when watching cable TV

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Hi,

I have the Magnifi Max SR soundbar connected to the Samsung UE65MU8002 TV.

I use both the optical cable and HDMI one to connect them together, as a single HDMI one plugged into the ARC sockets in both TV and a soundbar all of a sudden stopped working some time ago - TV did not recognize the soundbar and it did not turn on.

So I plugged HDMI in the ARC socket in Polk and in the standard HDMI socket on my TV and also connected them with the provided optical cable. My TV uses One Connect box.

I have a few questions:

1. It seems like I can use all TV apps (Youtube, HBO Go etc.) in the Dolby Digital sound system (which in my opinion plays the best for Polk), however when I watch TV from my cable provider (UPC), the option to turn Dolby Digital is not available on my TV.

I have Dolby Digital enabled on my provider's decoder and I have the decoder connected with my TV with the HDMI cable.

As the Dolby Digital option is in the decoder settings, it looks like I should be able to use it with Polk.

Does it require a special connection? What should I do to enable it for my cable tv? On my cable tv only the DTS Neo 2:5 option becomes available when using Polk and only after I manually turn the TV loudspeakers off.

2. Why don't my TV loudspeakers automatically turn off when I turn Polk on? Every time I have to manually turn them off in the TV settings which is a bit annoying.

3. Why does Polk (even with the current set up) automatically turns on (it should only do this with the ARC connection right?) - not only when I turn my TV on but also without any reason sometimes? Is there a way to turn it off in the way, so I can only turn it on with the remote controller apart from unplugging from the power cable?

Thank you for all your help in advance, much appreciated!