Complex sentence: Sherm spent the first season on the show as a writer, storyboard artist and director, then moved up to Storyboard Supervisor for the next three seasons of "SpongeBob SquarePants".
Split into simpler sentences: Sherm spent the first season on the show as storyboard artist, writer, and director. Then moved up to Storyboard Supervisor for the next three seasons of "SpongeBob SquarePants".