Excel Adding Comments
Comments are like electronic sticky notes that you can attach to the cells of your worksheet. You can add comments to the current cell either by clicking the New Comment button on the Reviewing toolbar or by choosing Insert → Comment.
Excel responds by adding a comment box with your name listed at the top (or the name of the person who shows up in the User Name text box on the General tab of the Options dialog box). You can then type the text of your comment in this box. When you finish typing, click any cell in the worksheet to close the Comment box.
Excel indicates the presence of a comment in a cell by displaying a red triangle in its upper-right corner. To display the comment box with the text of its note, position the thick, white cross mouse pointer on this red triangle, or position the cell pointer in its cell and click the Show Comment button on the Reviewing toolbar.
Most of the time, you see the text of a comment you've added to a cell only when you position the mouse pointer somewhere in its cell (as soon as you move the pointer out of the cell, the comment text magically disappears). If you want to display all the comments you've added to cells in the worksheet at one time, click the Show All Comments button on the Reviewing toolbar or choose View → Comments.
The comment boxes for all your cell notes appear in the worksheet until you click the Show All Comments button or choose View → Comment again.
If you want to keep the text of a single comment displayed in the sheet, select the cell containing the comment and then click the Show Comment button on the Reviewing toolbar. Excel will continue to display the comment even after you vacate the cell. To get rid of the display of the comment box, you must select the cell and then click the Show Comment button a second time.