Information
This policy setting governs the default format for new presentation files that users create. The recommended state for this setting is: Enabled. (PowerPoint Presentation (*pptx)) By default, when users create new PowerPoint files, PowerPoint saves them in the new *.pptx file format. Users can change this functionality by clicking the Office button, clicking PowerPoint Options, and then selecting a file format from the Default file format list. Disabling this setting allows users to choose from any of the available default file formats. If a new PowerPoint file is created in an earlier format, some users may not be unable to open or use the file, or they may choose a format that is less secure than the PowerPoint format.
Solution
To implement the recommended configuration state, set the following Group Policy setting to Enabled. User Configuration\Administrative Templates\Microsoft PowerPoint 2016\PowerPoint Options\Save\Default file format Impact: Enabling this setting does not prevent users from choosing a different file format for a new PowerPoint file, and therefore, it is unlikely to affect usability for most users.