You can use comments in a workbook in a couple of ways. You can add an explanatory comment to an item to track what you did or clarify it to others, or you can use a comment when you’re reviewing a worksheet to add any concerns or suggestions.
Move the mouse pointer over a cell that contains a red triangle in the top-right corner. Read the comment that appears.
If you can’t find a comment, or if you want to review several comments, on the Review tab, do any of the following:
Click Previous or Next to find and display a comment.
Click Show All Comments to display all the comments in the worksheet.
With a comment displayed, click Edit Comment to modify the comment. (The New Comment button changes to the Edit Comment button when a comment is selected and displayed.)