I don’t believe he HAS changed his mind, not really.
Not only has he not changed his mind, he denies he ever said it. Biggest example is abortion. He says he is prolife always has been, yet there is so much evidence to the contrary you would think he’d explode for the weight of it, but he keeps denying he ever said he was pro abortion.
When there is evidence in word and deed that someone has said something and they keep denying it, that person cannot be trusted.