We have 2 new QP's. They were doing great when they arrived. They are about 13 - 14 months old and as far as we know have always been caged together. We used to have sitting next to our parakeets cage and they seem to be fine. Then with in the last week one of the QP became very grumpy with us. Snapping and biting at us. We just kind of left him alone and handle the one that wanted to be handled.
Luigi(the grumpy one) would get jealous and finally come and play and be fine. But when we just work with one of them out of sight from each other they scream for the other one. Like they are asking where are you I can't see you. What to do? I don't want to stress them out, but want to work more with them.

Sounds like they are a bonded pair and the only way to stop this behavior is to separate them and keep them caged individually. Now, this is a personal decision and you should only do it if you want to. Some birds do fine with being caged together, others become bonded with each other so much that they don't want any human contact and will become aggressive to avoid it. So keep in mind that the longer they are caged together the longer it may take to 'win them over'.

Birds are not like dogs. Once a bird likes another bird and they are together dont come near them. Even same sex quakers can bond