The Apostle’s Creed was not actually written by the Apostle’s. It was given this name because what it teaches is traced back to the teachings of the Apostle’s and was used in one form or another from the very beginnings of Christianity.
Over time, places developed creeds for local use, while most these creeds expressed the same faith they differed in how that faith was expressed and some contained things that were contrary to Scripture. In the year 325 to address these issues and especially the question of who and what Jesus Christ is theologians gathered in a place called Nicaea. The result was the Nicene Creed.
The Athanasian Creed isn’t as well known as the other two in part because it is rather awkward to read. This creed was named for, but most likely not written by, a man named Athanasius. Athanasius was all about the Trinity and so is this creed. It lays out for us our basic understanding of the nature of God as God has revealed himself to us in the form of the Holy Trinity - Father, Son, and Holy Spirit.
So the Apostle’s Creed offers us a simple overview of the basics of what we believe. The Nicene Creed expands this with a special focus on the nature of Christ. And the Athanasian Creed makes sure we stay firmly grounded in a Trinitarian understanding of God.