Adjusting carb on a Troybilt TB90BC? ?

I purchase the correct tool for this, and there's three screws. 1" the Phillips" is obviously the idle. The other 2 "D shaped" are the ones I need help with. I need some sort of procedure for adjusting these screws correctly? The trimmer never ran correctly from the store, without the choke on half way all the time. I've replaced fuel lines and cleaned out the carb. It does run, but needs to be dialed in for sure. Any help with this would be great, as I can't seem to find a service manual for this machine to find out which screw does what?