Turn on change tracking for a workbook
Be certain that you want to use this method before continuing. Shared Workbooks have limitations, and one in particular is the inability to edit using Excel for the web. Therefore we highly recommend co-authoring, which is the replacement for Shared Workbooks.
Click Review > Share Workbook.
Note that in newer versions of Excel, the Share Workbook button has been hidden. Here's how to unhide it.
In the Share Workbook dialog box, on 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 that you want to keep. By default, Excel keeps the change history for 30 days and permanently erases any change history that is older than this number of days. To keep change history for a longer than 30 days, enter a number that is larger than 30.
Click OK and, if you are prompted to save the workbook, click OK to save the workbook.