Ducks are like that. Some are friendly some are not. Most are curious. I only have one (muscovy drake) who demands attention and likes to be cuddled. But all the others come when i go into the back yard or call them from the gate: they are nosy. All, now, go to bed in different compartments of my duck house without much fuss. I find that now they know the routine, adding new ducks each year us easy as they just follow the older ones.
Mine that demands attention was hand raised from 2 or 3 days old and didn't get ducky friends until he was 6 weeks old. If the truth be told, he thinks he should live in the house and not in the coop with ducks!!
I agree with @Evadig, spend time with them sitting down so that you are not towering over them. Curiosity will likely attract them over to see what you are doing. I spent many hours sitting on the back steps with my ducks, the first 2 years I had them. I can't do that so much now as I got puppies that need my time too.
Don't rush them. Just spend time with them, and accept yhat they are not going to be cuddly, just friendly