I agree, this is not a "user setting", why do you think you need to adjust this?
It is not an "idle screw" like a carburetor used, there are no jets on a fuel injected engine.
With engine warmed up completely, and idling, unplug IAC valve, idle should drop to 500rpm, if engine stalls, adjust screw to open throttle slightly then plug IAC back in and restart engine, repeat procedure.
With IAC valve unplugged rpm should not be higher than 600.
Unhook battery for 5 minutes to reset computer, or if you have an OBD reader reset computer, computer will need to relearn TPS(throttle position sensors) low voltage settings.
It will do that if reset.