My dad seems to have accidentally turned it on somehow and we can't find any option to disable it anywhere. Google only brought up results for the "YouTube TV" app, unless I just didn't search correctly.
There's no narrator on any of the other apps on the TV, so we figured it's some setting with YouTube. Help?
Check your device's Accessibility settings. That is where functions for people with visual disabilities can be turned on or off.
I dont know which Android TV device you are using so you'll have to look through your settings to find it. On the Shield TV, Accessibility is under Device Preferences. If you have another device, just look for it in your settings or do a google search for where to find it on your device.
Depending on what device you are using, you may also have an Accessibility setting in the Youtube app. For instance, on my Android phone, under settings, there is a choice to show Accessibility controls in the player. I don't see that setting on my Shield however.