Tap the ... button in the top right corner of your daily log
Tap "Reorder Meals"
Tap and hold on a meal to reorder it.
These changes will apply only to the ordering of meals this particular date.
If you want to edit the order of recurring meals so that the change applies to every day moving forward, then go to Profile > My Goals > tap into your goal > tap and hold on a Goal Meal to drag it to a new position. Changes to your Goal Meals will automatically apply to all days moving forward.