Looking at Common App, the schools each seem to ask about intended Major. Is there anything binding - assuming you are applying to School of Arts and Science (not something specialized like engineering, nursing, or business). S18 is 95% sure of major but it could change. But, putting “undecided” might be a negative. Plus a few of the schools then give space to write an optional paragraph about why you are interested in this area which gives another chance to show more of himself. Any thoughts?