Hi @BNBMove, welcome to the Sonos Community!
Sorry to hear that you’re having issues using your Sonos Amp with your TV.
Many TV’s will automatically select the audio device connected to the HDMI-ARC/eARC port to be used as their output device, disabling TV speakers and any other output device. Though this should mean it’ll default to the Sonos Amp if it’s connected to the ARC port, not the Sonos Arc which isn’t.
My first recommendation is to disconnect the Arc from the TV and just leave the Amp connected to see if that works. If so, you’ll need to manually change the TV speaker output to the Amp when both devices are connected.
A question I do have: is there a reason you’re connecting multiple Home Theater devices to your TV? You’ll need to keep adjusting the TV settings to swap between the two devices depending which you’d like to use at the time. While I can’t recommend any specific model, a HDMI switch seems to be the solution for you here.