Use the Notes pane to add reminders, talking points, or other pieces of information about some or all slides to help you in front of your audience.
If you want to format your notes (for example, to make key words bold or change the font size), use the Notes pane in Outline view (click View > Outline View > Notes).
When you type text in the Notes pane and then change the formatting of the text (if you change the font size, for example), PowerPoint might not automatically show your changes. To see your formatting changes, in Outline view, right-click the pane that contains the thumbnail images of your slides, and click Show Text Formatting.
You can then see the changes that you made in the Notes pane on a given slide, and make additional changes that you can see in the Notes pane immediately.