New to Windows 11. .

Hi LouiseShields1,

Thank you for reaching Microsoft Community. 

For us to better understand the issue, please allow us to ask the following:

1. Are you referring to Slideshow feature in Photos app? Or this a slideshow in desktop background?

2. Are you using a specific application in Windows for Slideshow?

You may also send us a screenshots or screen recording of the issue.

You can use Microsoft PowerPoint to record your screen: Record your screen in PowerPoint 

We look forward for your response.

Thank you for choosing Microsoft. Have a great day and stay safe! 

Sorry, (thankfully) I don't have Win11, but in Win10 here is the setting to check:

In start menu:

• type Settings

• In the search box, type "background"

• On the "background" page, try changing the setting in "Choose a Fit"
  

Some of the options will cause the problem you describe.

Hello and may I thank you for such a quick response to my question. The slideshow I'm using is in desktop. However, I've tried following the advice submitted by 'ronski2' and lo and behold I seem to have a result! This is the first time I've asked a question of the community and I'm very impressed with the results. Some of us older user can use all the help we can get.

Yours in gratitude, Louise

Happy to help.

This is a great place for 'personalized' help. But you should also invest some time learning to use internet "search engines" like Google, Bing, DuckDuckGo (yes they have silly names) and others. Search engines let you do focused browsing to find information on subjects of interest. "Play" with them and find one that works for you.

.

These internet search tools are like the index at a library. If you learn the logic of the index, you can find anything. Learning even a few simple search tricks will help you focus your search.

ie