"I have a new board and wonder what the different stance option are for!"

• Board stance is a matter of taste but also depends on factors such as board length, rider length and riding style.In general a wider stance gives better control over the board, especially in landings. That’s the reason why you see a lot of competition riders use a wide stance. The maximum stance is determined both by how wide you can stand and still feel comfortable, and by how long your board is. The wider the stance, the less board is left between the front foot and the nose. If you set the stance too wide for your board the nose will dive easily.
  For wave riding with surfboards a wide stance is often an advantage since it makes it easier to dig in the rail and keep the control over the board in hard bottom turns. For strapless riding in waves, a wide stance is required to keep the nose of the board from bouncing. A narrower stance is often preferred by beginners/intermediates and gives a smoother ride since there is more nose free to flex on the board. Also, it feels less strained riding with a narrower stance, at least if you’re not used to a wide stance.