You can choose which file format (such as .pptx or .odp) you want to be the default when you're saving your presentations.
Note
Not all features are supported in OpenDocument format. For more info, see Use PowerPoint to open or save a presentation in the OpenDocument Presentation (.odp) format.
Switch your default file format
- Select File > Options.
- Select Save.
- Under Save presentations, in the Save files in this format list, choose the file format you want to use by default.
See Also
Use PowerPoint to open or save a presentation in the OpenDocument Presentation (.odp) format