Apple TV 4K second gen

It is set directly to a Samsung TV with 8K high speed Hdmi cables and down through arc channel connected to a Marantz SR 7009. The problem that I have for example is if I start watching Tv I will have the stereo format shown on my marantz display, then I start Netflix and start a movie with Dolby Atmos, after the movie I ask Siri to change back to TV and the receiver still says Dolby Atmos when it should say stereo.