You can change the task order by using drag and drop.
If you hover over a task, you will notice six dots on the left side. Once you move your mouse over them, an arrow will appear and you will be able to change the order of the tasks or move them to a different task list in the same project.
Task lists can be re-ordered by using the same principle.
NOTE: You can't reorder tasks if they are sorted alfabetically. Make sure to unsort them first, by clicking on the up and down arrows near the Task area.
NOTE: You can also move tasks to a different project.