Combine the AV system with the variety of places on might have audio or video, and it is even more confusing.
I'd like to see a web site or an app that lets you input what you've got and how it is connected, and then answers questions about that setup for you.
For example, I'd be able to tell it that I have:
Denon AVR-1913 receiver
Comcast X1 cable box
Sony BDP-S390 Blu-Ray player
Nintendo Switch
Samsung 55U7000 TV
I'd be able to tell it that the receiver is connected to all the rest by HDMI, and that the TV also has an optical audio connection back to the receiver.
I'd also be able to tell it that I have an iMac, iPad, iPhone, Apple Watch 4, Surface Pro 4, and a Windows 10 desktop. I'd be able to tell it that I have WiFi that the all of those are on as is the Nintendo Switch, and an Ethernet that the iMac, Windows desktop, receiver, cable box, Blu-Ray player, and TV are on.
Finally, I'd be able to tell it that I have an iTunes library on the iMac, an iTunes account, a Netflix account, Amazon Prime, and Spotify.
The site would then answer questions based on that. Typical questions might be:
"I bought movie X from iTunes. How the heck do I watch it on my TV?"
"I don't own a copy of X. What are my rental/buying options using the services I currently have?"
"I have a photo gallery on the iMac. How can I view the photos on my TV? When doing so, how can I control the viewing while not at the iMac?"
"I want to listen to music while sitting on the couch. The music comes from a playlist on my iMac, and I want to be able to play/pause, and to skip tracks. How can I do this?"
Ideally the site should also be able to suggest improvements. For example, for the setup described above it might suggest that I connect the Comcast X1 directly to the TV, because they both support 4K. The receiver does not, and so my current setup can't do better that 1080p.