Look around the space where the birds are kept and try to access if there is anything in the area that might make them uncomfortable when out of the cage. You have to look at this from the birds point of view because things that are normal and usual to us may not be so to the birds. If there are other people and/or pets around making the area uncomfortable by too much noise and activity they may not want to come out of the cage. You just have to take it at their pace. If they will step up onto a perch you could try having them step up in the cage and slowly bring them out and place them on top of the cage and if they go back into the cage just let them be where they are comfortable.