Unless this has changed recently you may be confusing turning off autoplay (Of the next episode) with autoplay of the trailers for shows as you move around the home screen.

The second is the annoying one without an off switch that I could find within the xbox app

Maybe he means like autoplaying trailers when hovering over a title on the Apple TV? It's impossible to turn off and will autoplay if you don't actively move to a new title pithing seconds. If I can't find something to watch right off the bat then I leave the app and try something else because I can't stand it.

I also only use the Apple TV remote, which doesn't have a mute button and adds to the frustration. If I really want to watch something on Netflix, I'll turn the volume all the way down before going to browse for stuff.

Where? I can only find auto-play next episode (which is usually what I want).

I think this is a splendid demonstration of what follows when a service goes from good defaults to bad defaults, and leaves you the user to check the box to change it back. FWIW.

Is there a way to do that for the Netflix app on the fire stick? I can't seem to find it.