Perhaps if you had read the second link I posted it would have lead to a better understanding of how this all works. The “2 channels” is how many LPCM channels the input device supports, not how many audio channels is being output. You said you were using ARC which is limited to transmitting uncompressed stereo, or surround sound compressed with AC3 or DTS. I outlined how to get surround sound over ARC via AC3.
If you wanted HD audio support you would have to either plug the Vero directly into the AVR or else have both an AVR and TV that supports eARC.
If you have CEC enabled your TV likely is able to switch sources on your AVR connected devices.
This is not a normally supported feature of any media player that is not made by Apple. You could search out how to do it, and you might be able to get it to work, but likely it will end with you frustrated by it either not working, or not working well enough that you wouldn’t go back to the normal way this equipment was designed to be used.