Font styles help you customize the way text appears in a PowerPoint document. You can manage the fonts on all slides in your presentation by updating them in the slide master. The updates you make to the slide master will be applied to the slides that use it. If you only need to update fonts on a single slide, you should change it on the individual slide only. You'll need to update each slide manually to apply that style to it.
Changing Font Styles on All Slides
Open the file you want to edit in Microsoft PowerPoint. Then go to the slide master by selecting "View," "Master" and "Slide Master."
Click on the slide master's title. Then choose "Format" and "Font" from the toolbar. The "Font" dialog box will open.
Pick the font and styles you'd like the title to use, then click "OK."
Select the body of the slide master to edit its font style. Update the font through the "Formatting" toolbar or "Font" dialog box. The style will be applied to your PowerPoint slides.
Change Font Style on Single Slide
View your slides by selecting "View" and "Normal." Then go to the slide you want to update.
Select the text that includes the font you want to change.
Choose the font options you want to modify from the "Formatting" toolbar. The font will be updated on the selected slide only.