If you wish to use the HDMI ARC functionality of your TV, please use the "HDMI 2" port on the back of the TV.
Please ensure that your Surround Sound system is also ARC compatible, and that the HDMI cable is plugged into the HDMI-Out port on your amplifier.
From there, ensure ARC is turned on from your amplifier menu (if you have the option), and you should have no issue receiving the audio from the TV.