Tools/materials: Dell XPS 13-9350-3708, win 10, PPT8.75.
1. Open the PPT document whose master needs to be modified.
2. Find the view option in the menu bar, and then click Enter.
3. Click the slide master in the master view.
4. Enter the design modification settings for the slide master.
5. Click the slide size in the menu bar set by the master to select a custom slide size.
6. Modify the size value, and click OK to complete the modification of the size of the master slide.