If you have ever inserted a link to another file
on a PowerPoint slide -- perhaps to bring it up on the screen during the show -- then each time you open your presentation, you will be asked whether you want to update this current presentation with the changes to the linked files. When you agree in this dialog box
, you are saying to change my PowerPoint presentation to show the latest info in the linked file.
Read more about updating PowerPoint with links to other files
Add an Excel Chart to Your PowerPoint Presentation
Using Paste Special Command When Copying Content into PowerPoint
How Do I Use a Hyperlink to Open Another Presentation Seamlessly?