In one sentence, describe what the following article is about:

Follow the instructions under "Displaying Comments" for your version of Microsoft Word. If you cannot see the complete text of the comment in the comment balloon, you can turn on the Reviewing Pane to review the complete text of your comment there. See the instructions under "Displaying the Reviewing Pane."

Summary:
Turn on the comment display, if necessary. Click the balloon whose comment you wish to edit. Make the text changes you want.