Is there a way to change the order of the tasks?
Can I change the order of the tasks within the same priority?
For example, I tried to number them but that did not work.
What is the default order of tasks and can it be changed?
in order to reorder tasks within the same priority and without a due date, you can click "reorder" at the bottom of the project view and after reordering click "done reordering" (or toggle the reorder mode using the "r" shortcut key).
Note, this will work in the project view and only for tasks without due dates.
If you have multiple task set for the same day within the same priority, you can use times to order them, using such dates as: "ev day @ 14:30" or "tomorrow @ 16:00" etc.
Still, since this is rather a workaround than a permanent solution, you're welcome to vote for a previously suggested feature request to sort tasks by name: