BU and UW school change...

<p>ive been accepted into both BU and UW School of Engineering...BUT, i wish to (sooner or later...) change my major to economics, or some sort of political science...do i have to call and change (or even apply again) schools or am i ok and just have to declare my major my junior year as such...? and if i do just go to the School of Engineering, must i take engineering classes?</p>