I see some poor editing in hairs of second girl (very bad background removal) ... if you want to ease this process, put one softbox from behind her and then you'll be able to make white background very easily). Or in situation like this, when shooting is done, play in postprocessing with hair selection more (white it with not only brush and masking, but also brightness/contrast, new layers, partial selections and blending modes of that part of hair to make it look real). Because this part of picture is really horrible.
This is example:

P.S. and whiten eyes less, looks unreal
P.S.2. and you forgot to whiten background on pic #4 between her left arm and torso