The current way of reordering is not intuitive or easy, as you need to remove all the divisions then add them in the order one-by-one as you want them to appear.

As suggested by Tim from Queenscliff Boardriders, it's not easy to know how to do this:

We've added divisions to our club over the last few years, and we'd love to be able to re-order them in the signup form - people aren't finding them because they're not in order. Love to add this as a feature request.