Changing column width in one sheet in a shared workbook

Excel 2010 question:

Several people are sharing an Excel Workbook. They each have their own sheet which they update. One user is changing the column width from 24 to 30 in her sheet. Then saves it. If she opens the document later in the day (same day), the column width sticks, but when she opens the workbook the next day, it's back to default. We have set up tracking, but that only tracks content changes not column width changes