Customizing the visual backdrop during video calls for privacy or presentation
Hello Mary,
My name is Jackson, and thank you for your question.
I sincerely apologize for the issue with customizing your background.
The option to customize or blur background in Teams is device specific, If you don't see this option in the menu, the feature might not be available on your device. Your computer processor needs to support Advanced Vector Extensions 2 (AVX2) for more information check with your computer manufacturer.
See more details in the link;
https://support.microsoft.com/office/f77a2381-443a-499d-825e-509a140f4780
Warm regards,
Jackson E.