hey dude, yeah i get teh same problem and theres a few tricks to it, one is tat weird craft glue tats all rubbery and smells yummy, glue teh back of teh pin over the needle bit and it forms a lock around it, another is pliers which i use, bend the needle tip like a hook over the hoop ye put it through so you cant unhook it
theres another way wit' teh pliers where ye bend teh hoop down after you put teh needle through so ye gotta push te needle further in to get it to unhook but i dunno how well it works, good luck though man
slante'