A family of Microsoft presentation graphics products that offer tools for creating presentations and adding graphic effects like multimedia objects and special effects with text.
Unfortunately, PowerPoint for Mac does not have a Disable hardware graphics acceleration option on the Set Up Show dialog, it's only available in PowerPoint for Windows.
Try creating a new user account (System Settings>Users & Groups), signing in to that, then testing if the problem still exists. If it goes away, it's an issue with the user profile part of your Office installation.
If the issue still exists, or you'd rather not move your user data to a new profile, try uninstalling Office following these steps: Uninstall Office for Mac Then reinstall from the Subscriptions page of your Microsoft account
Posting a screen shot showing the effect you're seeing may give us more information about the problem..