On the Review tab, with the presentation open in Normal view, click the Show Markup button if it isn’t already selected. (If the button isn’t available, the document doesn’t yet contain any comments.)

Click or select where you want to insert a comment.

Click the New Comment button.

Type your comment, and then click outside the comment when you’ve finished. Continue adding your comments to the presentation.

Click the Next or the Previous button to find your own or other people’s comments.

To edit a selected comment, click Edit Comment, make your changes to the comment, and then click outside the comment.

To delete a selected comment, all the comments on the slide, or all the comments in the presentation, click Delete, and, from the drop-down menu, choose what is to be deleted.

Click the Show Markup button when you’ve finished. Any comments remaining in the presentation will be hidden until you’re ready to review them.