Which of these, other than the president has used the executive office to further improve America as well as its standing in the world?

speaker of house

secretary of treasury

secretary of defense

First Lady

Apart from the President, the Speaker of the House has used the executive office to further improve America as well as its standing in the world.

Explanation:

The Speaker of the House is the leader of the lower house of Congress. It is second in the line of presidential succession, just behind the Vice-President. On rare occasions, as due to their investitures both the President and Vice President must leave the country, or they are temporarily unable to make decisions, it is the Speaker who assumes in fact and until the chain of command is re-established the executive function of the country.

Your answer is Speaker of House.