Help, please. 1. A 7 page excel spreadsheet. ?

Somehow, after I added data the first 3 pages of worksheet were uniform with same width, length across page. But the last 4 pages got smaller and held less infomation. I looked in page preview to see if the margin settings were the same and they were. I picked a solution when I asked the office assistant. The worksheet originally had 5 columns of information on each page, now it has been compressed all the way to the left instead of full sized.