...
Every member in the organization structure has a main department. It is marked with "M" in the Member Edit page if the member belongs to multiple departments.
...
And department Department leader is set as an attribute of departments, can be modified in the Organization Structure inteface.
...
Assign to the main department assignee of current assignee
And department Department assignee is set as an attribute of departments, can be modified in the Organization Structure page. Transfer the issue from current assignee to its main department assignee.
...