Can't Modify Basic Input Remote

[guy151]

I'm trying to modify the basic input remote to add a middle mouse button, but I can't seem to see any changes I make take effect. I'm not even sure if I'm modifying the correct remote. I'm in the Basic Input folder, but the layout file doesn't seem to correspond to what actually is displayed in the app. But I don't see any other remotes that would indicate it to be the correct one to make edits on.