Sounds a lot more like you're plugging from the cable box to the surround sound. So it always plays from it. You need to plug a cable from the tv to the soundbar. (You can actually plug everything directly into the tv then go optical audio to the surround sound and whatever is on the tv will automatically be on the surround sound without changing inputs)
One normally assumes audio should follows TV, but not always. i.e.: I have an exercise video that I follow but don't need to listen what the trainer says, I heard him the first time, but much rather listen to the basketball game.
So it depends how u have yours hooked up and your expectation as far as what you have to do, how many buttons you have to push? to get the desired result.