Before the custom Keybinds patch you could change the "Attack Next" key functionality which I did by binding it to just Q for simplicity because it is superior to regular Attack in every way.
Well, when the Keybind update came around Shift+Q did nothing for me and Q just functioned as normal attack and there was no way to bind a key to Attack Next.
Well I recently found out how to re enable Q to turn into Attack Next. I went into key binds menu and unbound Q from attack, so I have no Attack option at all but when I push Q I get the Attack Next functionality back. My guess Is i still have some config file somewhere with Q bound to Attack Next and the keybind update had over wrote it.