Absolutely agree with all the above,know it's hard to get used to but have some patience,it's only been 3 wks and they have gone from being in a confined cage no doubt with people poking fingers thru etc and having not much human contact,proper human contact and now they have a home and human contact as they should,he/she is probably still unsure at how to be and is reacting the only way he/she knows how and just needs lots of reassurance,they may have been removed from mum at an earlier stage and now see you both as their parents which you are,you just have to give yourself time to get used to having kittens around and vica versa,some kittens are needier than others and are more vocal,what you think is he/she crying might just be he/she talking to you,plz give he/she time and more understanding and i'm sure he/she will settle down once he gets used to things,plz don't give up on them,hold out it will be worth it
And theirs enough experienced peeps on here to moan to or ask for tips/advice,these little kitts need you so much