Sexing angels that are not breeding is almost impossible. How big are these?
Pic 1 looks like a silver veiltail
Pic 2 looks to be a marbled
Pic 3 looks like it could be a golden, perhaps a better pic would help.
What size tank are they in?
Tankmates?
Feed them a high protein diet, perhaps a good quality flake or pelleted food with bloodworm and brine shrimp. Keep you temp on the higher side, maybe 27-28C and frequent water changes should see them grow and color up nicely.