@georgie67 aaah the shuffle button xP ok...
When you first click on that button it randomly sends you to any story here on Wattpad, they can be popular or not popular, it is random.
Then a black bar will appear on top of the page giving you 3 options first one is to choose the cattegory (romance, horror, etc).
Then you can choose if you want it to show you the stories on that category, people who write that type of stories or both.
If you have any more questions, don't hesitate to ask.