On the Events Meal Categories list, drag a row by the arrows handle in the first column and drop it where you want it. Sprwt saves the new positions immediately and shows Order updated with success; the moved rows are briefly highlighted. The drag handle itself is only shown to users with the Edit Categories Meals permission (Kitchen Settings group); if you don't have it, set the Order number on each category's edit page instead. Categories without an order number are listed after the numbered ones.