And that's exactly how it is supposed to be, good job. You do not even need to use choke when the weather is warm
For the adjustment screw, are you referring to the idle mixer screw or the throttle? Throttle - screw goes in, raises the throttle, idle gets higher. Mixture - can go either way, depending upon the conditions. If the screws are not responding, there could be something wrong with the carb assembly. I once had a carb where the DIY fix of the accelerator pump, by previous owner, prevented the throttle from closing all the way, so the idle screw was not responsive at all because the fuel was already going through the main jet circuit on idle.
So, the engine does not have higher RPMs? Both, while in motion and on idle, or only in motion (under load)? Were higher RPMs fine before you fixed the carb? Does your throttle open all the way, when you push the gas pedal to the floor? Happened to me once ?