You might feel silly doing it, but Xouie has a good point about mimicing their sounds. When my wife and I feed them, we make their 'special treat' noise (It sounds like b-b-b-b-b-b-b) and they come running to get some food. Predators don't do this. We also join in on their evening scream, but it's mostly for a laugh!

Also talking calmly to them at a low volume is a near constant around here.
Have you tried eating with them? That's something else we do here at home. We sit on the floor with them and feed pieces of apple or whatever fruit we're eating. If they won't approach to take food from your hand, simply put it on the ground a short distance away. They'll start competing for it sooner or later, and you'll have them trying to steal food out of your mouth if you're not careful.
I'm sorry they get skittish for you! I have noticed that ours do go through a phase when they don't want to be held around puberty. I've just never stopped to consider it! They always go back to being lap-warmers after a week or two.
When you do hold them, make sure they are at eye level, and pointed toward your face, eye to eye. This seems to be the most comfortable way for them to be held in my experience. They also like having their heads loosely cupped, as if they are in a hand tube.
Reading over this it all sounds incredibly weird! But please try it, it works. Coturnix quail, out of all the birds I have ever owned, are the number one tamest, most cuddly around. I'm really frustrated for you, I wish you could enjoy it!