If I was class president for two years, do I write those as one activity or do I separate them on the activities section of common app and UC app
The Common App doesn’t have much room for extra curricular activities. I would list it once but be sure to state that you held the position for two years.
I would do the same for the UC app unless you have empty space. There is space for 20 items and you have approx 350 characters to describe what you did. Would your description both years be the same?