Final answer:
Commanders require proper authority to make personnel changes, often coordinated with high-ranking officials or the President, who serves as Commander in Chief, or with the Joint Chiefs of Staff, who are key military advisors.
Step-by-step explanation:
Commanders must not attempt to swap out individuals without valid permission and coordination with the proper authority within the military hierarchy. According to the information provided, the President of the United States serves as the Commander in Chief of the Army, Navy, and Militia when in active service. This role includes significant responsibilities such as requiring opinions from principal officers in the executive departments and the power to grant reprieves and pardons. The description also mentions the role of the Joint Chiefs of Staff who are principal military advisors to the President and consist of high-ranking military officers from the Army, Navy, Air Force, and Marines, along with a chair and vice-chair.
For any changes to personnel, coordination with the applicable command structure is essential, and for high-level matters, it may even require presidential approval or coordination with executive department heads responsible for the armed forces, such as the Secretary of Defense or the members of the Joint Chiefs of Staff depending on the context and scale of the personnel changes.