Once you click on Optimize plan, the system will give you the best possible result according to the conditions and restrictions you have set. However, you may still prefer to edit the order of the stops.
That said, you can modify the order within the same route, or between different routes.
This procedure can be done as follows:
Go to the Edit section within your plan.
Select the stops you want to move (it can be one or multiple).
Keeping the button pressed drag the stops to their new position.