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.
Hi, Elizabeth Grant1
Thanks for posting in the community.
Change the default program:
You can try changing the default program to open PowerPoint files. Right-click your PowerPoint file, select "Open with", and then select "Choose another app". In the pop-up window, select PowerPoint 2007 and check "Always use this app to open .pptx (or .ppt) files".
Check file associations:
Make sure your file associations are correct. Open Settings > Apps (or shortcut: Win+I), select "Default Programs", then search for .pptx (.ppt) in "Set defaults for file types or link types", and then select Microsoft PowerPoint below.
Please feel free to let me know how it goes.
Best Regards, Zain.M - MSFT | Microsoft Community Support Specialist