Mormon doctrine teaches that God continues to reveal new information to humanity. This means that the Bible has, for Mormons, been superseded by the Book of Mormon, the Doctrine and Covenants, the Pearl of Great Price, as well as continued revelations reported by LDS Church prophets.
Read Article: Mormons Believe in Continuing Revelation from God
“What really sets Mormons apart from traditional, orthodox Christianity is the belief that new, valid revelations can supersede previous revelations.”
I think it is worth pointing out that the Catholic Church also believes in new, valid revelations that can supersede previous revelations. The doctrine of papal infallibility allows the Pope to make proclamations that supersede previous doctrines or revelations.