Question

2. How is the Constitution a living document even when the text remains the same?

Answer 1

The president can change things in the Constitution through executive order.

This is technically the answer, though I don’t especially like how it’s worded — a “change” in the Constitution is an amendment. The president can make amendments to the Constitution to reverse previous amendments or create new ones. Even with this power, though, the president still has to go through the people, the House of Representatives, the Senate, etc.; executive order.