When importing PowerPoint files into Presenter, slides may not display clearly at first. This is typically due to image sizing within the PowerPoint file and can easily be fixed.
If you are running Presenter on a Windows computer, you'll see a Launch with PowerPoint button in the top right corner when you have PowerPoint open. This is the recommended solution (not available for macOS users).
If Option 1 does not resolve the issue or you are working on macOS, please follow Microsoft's instructions to change the size of your PowerPoint.
Some tips to add to Microsoft's instructions: select Widescreen from the drop-down menu for "Slides sized for:" and then manually increase the Width and Height fields. Make sure to maintain the ratio between width and height, meaning, if you double the width, you'll also need to double the height.