Hi @Cindy Wang
Do sliders shown on external monitor in Normal mode of PowerPoint?
Have you tried other screen casting modes, duplicate mode, extend mode and .etc?
I suggest you try following steps:
- Click Slide Show tab on Ribbon > Monitors group, check the option for Monitor. Besides, uncheck the selection of 'Use Presenter View'.
- Go to File > Options > Advanced, scroll down to Display and tick the box of "Disable slide show hardware graphics acceleration", click OK, restart PowerPoint and see if the issue persists.
- Locate to Windows System settings, check the Scale and Layout in Display settings. You may try 100%.
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