pic1: slender body, longer 1-4 spines on dorsal fin, extended dorsal fin (the end of it), anal fin extending into the caudal fin. Most probably male.
pic2: rounder body, 1-3 dorsal spines short although 4th high, rounded finish of dorsal fin (the end), anal fin doesn't extend into caudal fin. Most probably female.
pic3: rounder body, can't determine 1-4 dorsal spines (picture quality), potentially extended dorsal (the end of it), possibly extended anal fin (though doesn't look it). Most probably female.
It's hard to tell from the pics but if there is some pinkish colour to their bellies they are generally female. Pics 2 and 3 also seem to have a larger/rounder protrusion in front of the anal fin (don't know its proper name but my understanding is that it's pretty much their sex organ) which tends to indicate female too.