Since it's currently impossible to drag and drop tasks into an order you'd like them to be, by following the next few steps you'll be able to set the order of tasks to your liking.
Step 1: Load the Project
First, navigate to the "Saved Items" by going to the menu (☰) and then clicking on "Saved Items". Then, find a project where you want to change the order of tasks and load it.
Step 2: Change the order of your tasks and save the project
After your loaded your project, head over to your Master List as that's where you can change the order of your tasks, by drag-and-drop. To get to your Master List, click the link in the Sidebar, if you have it there, or press "M" key on your keyboard.
Step 3: Delete the old saved project
Now that you've changed the order of the tasks and saved this as a new saved project, you should delete the old one. Simply, go to the "Saved Items" overlay and delete the one where tasks aren't in the correct order.