Armpit hair is growing back darker and some hairs are growing faster than others after waxing, why?

This was like the second time to wax so I was curious. Some hairs are growing back slow and thinner but, I just want it to be consistent. Is there anything I can do.Armpit hair is growing back darker and some hairs are growing faster than others after waxing, why?
all u hav 2 do is keep waxing. the hair root will eventually die and u will only hav 2 shave like once a week or wax once a month