Nothing is treated with more authority than the Scripture in Catholicism.
The words of the Apostles are the Word of God. 1st Thessalonians 2:13 KJV The Apostles yes wrote, but they also spoke; they taught, and they also approved, this latter Apostolic authorization is the reason why the New Testament contains books and epistles not written by any Apostles, like Mark and Luke and Acts. These were approved by the Apostles, so the Apostles authenticated them as the Word of God.
The Apostles instituted the office that would be tasked with preserving the Word of God for posterity, the office of Bishop. The bishops themselves teach that one pastorate presides over all the others, Peter's Roman pastorate, the Pope being the current holder of this office. The papacy is given the charism of infallibility to authenticate already existing ancient teachings as Apostolic, not to ever invent or introduce new teachings as the Word of God.
Before the Schism that still today divides the world's thousands of validly ordained bishops, all of the bishops participated either directly or by proxy in a number of Church councils. These councils were a 'comparing of notes' between the bishops, comparing what each of theirs own received Apostolic oral traditions were with one another. The councils therefore separated deficiencies in their Apostolic oral traditions and anathematized them, purifying the Apostolic oral tradition as a whole for all of the bishops then, and for all the future bishops who had not even been born yet.
