Males have more markings on their face and usually have more elongated fins as well (meaning they have a longer "tail" at the end of their fins. Sorry, I don't really know how to put it into words lol). Regardless, the most accurate way would be by the intensity/amount of markings on the face but there is no way be 100% sure. You should be able to make your judgement when they fully develop their coloration which would mean they would be about 4 inches but it could vary depending on their health and water quality. If you post a picture I'm sure other members would help you decide the sex of your fish.
Females will have solid colored cheeks and faces, males will have striations and markings on the cheeks and face. Fin length is not an accurate way of sexing because dominant females will develop trailers on the anal and dorsal fins, too.
The facial marking method does not work as well with super reds or mouthbrooding severums. Super reds tend to have spotting on both males and females. Mouthbrooding severums (Heros severus and Heros sp. 'Atabapo') sometimes show differences between the sexes, but I have a pair who show no physical differences at all. The only way I can ever tell is to see which one lays the eggs. I still cannot tell them apart when they're not spawning.
Usually severums will start to color up around 3 - 4". By the time they're around a year old it should be pretty obvious by looking at them.
Ok, with that info, I'm pretty sure the gold is a male, lots of red marking around the face area, but the greens are a bit smaller. I will get some pics when i get home and post them. With the way they interact, I'm guessing all males.
They all three look male to me. The only one that could go either way, IMO, is the top one. I've seen young females (especially in H. notatus) start out with spots on the cheeks, only to lose them as they grew. I doubt this will happen but there's a small chance.
The amount of striation on the bottom green says male, though. The gold's spotting will probably darken and turn more red as he grows but I am guessing male on him as well.