Everythings in this world change, with time the nature goes dim, only constant will remain the same,  tell me why nigerian elders believes cultures shouldn't change?

I think because the truth is bitter and better,

Because why change, when you can have both? Look at Asian cultures, that are modern in many ways but still have their culture mixed with it. They even have many areas with their famous style buildings from centuries ago, as a reminded of their past.

culture should change to what exactly?

explain yourself better because if what you mean is gay marriage, licking myriads of privates all over the place, legalizing cocaine and such, then you might need to remain overseas and be free there.

when culture changes, it's no more culture
MY Igbo people say, '' ihe yiri ji, abughi ji''
that which resembles a yam is not yam,
it's either you have a culture, or you have none, there's no in between