From MS Excel Help --
Turn on change tracking for a workbook

On the Tools menu, click Share Workbook, and then click the Editing tab.
Select the Allow changes by more than one user at the same time check box.

Click the Advanced tab.
Under Track changes, click Keep change history for, and in the Days box,
type the number of days of change history (change history: In a shared
workbook, information that is maintained about changes made in past editing
sessions. The information includes the name of the person who made each
change, when the change was made, and what data was changed.) that you want
to keep.

Be sure to enter a large-enough number of days because Microsoft Excel
permanently erases any change history older than this number of days.

Click OK, and if prompted to save the file, click OK.

Note Turning on change tracking also shares (shared workbook: A workbook
set up to allow multiple users on a network to view and make changes at the
same time. Each user who saves the workbook sees the changes made by other
users.) the workbook.
This always works for me and I have a massive bonus spreadsheet that
several people work on.

"Leon" wrote:

On a monthly basis I get a detailed and lengthy spreadsheet sent to me. I
need to check if there have been any changes from the previous month. If I
could just do a €œcompare€� of these 2 so that any changes get highlighted it
would save a massive amount of time. Any suggestions?