How to change the order of the tasks?
Option 1 - Using the Sort feature
Open TickTick on your iOS device, then tap the option menu in the upper-right corner, then tap "Sort".
Sort tasks by due date, title, or priority if you're sorting the Inbox or a custom list.
Sort tasks by list, due date, title, or priority if you're sorting the "All", "Today", or "next 7 days" lists.
Note that tasks in a shared list can also be sorted by assignee.
Option 2 - Drag tasks to change their order
Repeat step 1 from Option 1 above and sort tasks by "Custom".
Press and hold a task to drag them manually.
How to resume the original sort after you drag tasks?
Use Option 1 above to sort the list the way you like it.