Polk Signa S4 Dolby not working.

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Hi!
I just bought my Polk Signa S4 soundbar today.
I came home and connected to my LG Oled C2 TV via hdmi (the cable that came included) in the eARC port.
But when I try to watch Dolby Atmos tests on YouTube, or Dolby Atmos supported movies on HBO Max it's still just the white LED that is lighting up. Not the green nor the cyan one.

What am I doing wrong here?

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