How do I see the 5 computers that are authorized to see my aTV content? I want to deauthorize old computers but the only options I've found is to deauthorize all.

There is not a list of names where you can choose which one you want to deauthorize. Your only options are to deauthorize a computer that you have access to or deauthorize all computer. To deauthorize a single computer it has to be done from that computer, otherwise you will need to choose deauthorize all. This will happen when you get rid of a computer and do not deauthorize or factory reset it first. All you need to do is deauthorize all, and then when each computer wants access to your Music or Apple TV, then it will prompt you to authorize it. There is no limit on iPad/iPhones and you will not need to authorize those devices.

Authorize or deauthorize your computer for Apple ID purchases - Apple Support

There is no option to see the names of the authorized computers.

Note with the "Deauthorize all" you will only need to reauthorized any computers (not iPads or iPhones) that you still have and still want to use.

Also see: Authorize or deauthorize your computer for Apple ID purchases - Apple Support