When you are inside a mission, on the Reports screen, there is a "Detailed Mission Change History" button. This will show a report of all the changed to that mission, field changes, , adds, deletes, who made them, when, etc.
Are you looking for the same thing for non-mission data? There is so many areas I think a detailed report of all Members, Tasks, Calender, Time Keeping, etc. would get a little overwhelming. Is there specific types of changes you are trying to track?
Mike