Who is responsible for making sankharas impermanent?

Sabbe Sankhara Anicca. But it is not clear why all Sankhara are impermanent? Can I ask ,who is responsible for making all Sankhara impermanent? Are we responsible for making the Sankhara impermanent? Is it some kind of God who is responsible for making all Sankhara impermanent? Or Does it happen on its own ?