Quoted here are words from Lumen Gentium:
This power (of the pope and bishops together) "is exercised in a solemn manner in an ecumenical council."

Which means that what an ecumenical council says is roof-top high authority, higher than a Pope by himself

Which is why many people were confused and saddened that a Pope, Benedict XVI,  took it on himself to reformat the teaching of Vatican II

Jesus, please help Pope Francis use authority they way you want him to use it