Moving a task can change its outline level. A task retains its level in the outline only when you move the task to follow a task at the same level.
Comparatively, if you move a lower-level task to a section of tasks at a higher level — for example, move a third-level task to a section of second-level tasks — the moved task takes on the level of the task preceding it. And the converse is true when you move a higher-level task to follow a lower-level task.