117 Powerpoint | How to insert comments onto my slide?

You can add comments for the slide as whole and to certain parts of
text. Simply have either the slide selected from Slides menu on the
left or select the text on the slide you wish to comment. Next
continue to Review tab and Comments section. Click on “New Comment”
to leave a comment. Note that all the comments are numbered. To
hide those comments from the view, click on “Show Markup”. To view
the comments, click on the same button again. To edit a comment
click on “Edit Comment” that is just next to the button “New
Comment”. - Office ToDo