Occasionally, you might start a story in response to a particular prompt, but it actually turns out to be about something else. You can change the prompt assigned to a story on the Add or Edit Story page. Scroll down to the Assigned Prompt field, pull down the menu, and choose a new prompt. Or choose My Own Topic if there’s no prompt (yet) that fits your story.
You can also suggest new prompts using the Contact link in the lower right corner of any page. Choose Story Prompt Idea from the Topic menu.