Hello there Murgi,

You would use Track Changes in Word.  Just click on Tools | Track
Changes.

In Excel, 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 to change history 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.

I hope this has been helpful to you.