Is it more proper for a US president with no military service to salute the flag during the National Anthem or place his/her hand over his/her heart?

Can The President Use The Military Salute?
Throughout most of America's history, the president has not saluted the flag or soldiers. Typically, the president has held his hand over his heart to show respect for the flag, like civilians do. However, as commander in chief, the president still has the right to render the military salute. It has become the custom of U.S. Presidents to salute soldiers when entering or exiting the Air Force One or Marine One. This started during Ronald Reagan's presidency in the 1980s. Members of the Marine One are required to salute the president as he approaches and exits the helicopter. Following the example of previous presidents, President Reagan would nod and say hello to the Marines, but he found it awkward that the Marines could not drop their hands. They had to hold the salute until he passed. Ronald Reagan decided to return the salute so the Marines could stand at ease. This, however, went against the protocol for rendering military salutes, since President Reagan was wearing his civilian clothes. Thus, before going against the regulations, Reagan sought advice from the commander of the Marine One. He told Reagan that, as commander in chief, no one would stop him from rendering the salute. Ronald Reagan soon began saluting military officers whenever he was entering or exiting the Air Force One and Marine One. The presidents that came after him have followed his example; Presidents George H. W. Bush, Bill Clinton, George W. Bush, and Donald Trump have all rendered the salute.