multichannel audio

Hi everyone! I've just acquired an Amazon Fire Stick Lite. It's plugged in my Samsung TV (model : UE32F6400AW) in HDMI 3. I also plugged in my Blu-Ray player / 5.1 audio receiver (model : LG LHB625M) in my TV HDMI 2 ARC. As a reference, Amazon Prime is pre-installed on my Samsung TV and sends...