I think giving the new glider a few weeks to get used to his new home and
all the new smells would be a good start.
Second idea, I don't let my gliders bite me if I think they are going to
bite me. the last new glider we had, connor, was very scared and crabby, came from
an uncaring home. I slowly feed him mealworms from a plastic plate. Let him
smell me, but NOT bite. after awhile I moved to petting him while he was busy
eating. then feeding him with my fingers, and letting him climb on my arm for
the treats. I didn't pick him up much, i let him crawl on me, and I think
he never bit me.