The Save commands default file format must be configured.

This policy setting governs the default format for new presentation files that users create. If you enable this policy setting, when a user creates a new blank presentation, it is in the specified default format. Users may still override the default and specify a specific format when they create a presentation. If you disable or do not configure this policy setting, PowerPoint Presentation is the default option.

Verify the policy value for User Configuration -> Administrative Templates -> Microsoft PowerPoint 2016 -> PowerPoint Options -> Save "default file format" is set to "Enabled: PowerPoint Presentation (*.pptx)".

Procedure: Use the Windows Registry Editor to navigate to the following key:

HKCU\Software\Policies\Microsoft\Office\16.0\PowerPoint\options

Criteria: If the value DefaultFormat is REG_DWORD = 1b (hex) or 27 (decimal), this is not a finding.

Set the policy value for User Configuration -> Administrative Templates -> Microsoft PowerPoint 2016 -> PowerPoint Options -> Save "default file format" to "Enabled: PowerPoint Presentation (*.pptx)".