Use Widescreen (16:9) or Standard (4:3) or choose a custom size for your slides.
Change the size of your slides - Microsoft Support
Add slide numbers, page numbers, or the date and time - Microsoft Support
Sizing PowerPoint file to match size it will be in a Word file
What Slide Size Should You Use? Presentitude, 59% OFF
Change the size of your slides - Microsoft Support
Change the default font in PowerPoint - Microsoft Support
What can I do if the information does not fit on the slide? - Quora
How to Change the Size of Slides in Microsoft PowerPoint
How to Change the Size of Slides in Microsoft PowerPoint
Record your presentation - Microsoft Support