CS/SA5 targetting problems

i have an issue with this vehicle, i lock target with T (Fix objective of radar/IRST) and fire a missile towards aircraft then when pressing Y(select objective for RADAR/IRST to fix) it swaps to target into the other munitions which i wanna destroy with AHEAD rounds but the 1st missile goes stray and into the second target missing the first one

how i do to lock the missile into the first target? it seems deactivating the radar works to some degree but when i press T to show the lead for AHEAD same thing happens, is there a way to show the lead of all munitions so i dont have to swap between them individually or something bcoz its very confusing when dealing with so much stuff from 2 or 3 planes or helicopters and the lead indicator seems to interefere with the missile path

(I dont use C+R interface)