Editing all properties of a task can be achieved by:

1. In your task list, tap on the task you wish to edit to view its details.
2. Tap the Edit icon to the right of the task name to enter the editing mode.
3. Tap the desired field (such as priority) and make your edit.
4. Tap Save to leave the editing mode.

You can also long-press a task in your task list to perform quicker edits of some properties.