As Purchaser or Editor you can rearrange when story prompts will be sent to the Author(s). On the far right of the story prompt is an up/down arrow. Simply click and hold that arrow and drag the prompt to a different order, releasing when the prompt is in the right order.

Keep in mind you can only resort questions that have not yet been sent. Those story prompts are easy to tell because those prompts are below the Pending Prompt line, the send date would be in the future, and the story prompts still has the send-now envelope icon.