Hi @John Schell.
Thank you for posting your question in the Microsoft Q&A forum reaching out regarding the issue with the persistent blue background in Microsoft Teams on your Mac.
When selecting “None” under background effects, Teams should revert to your actual environment without any overlay. If it instead defaults to a blue background, this may be due to a graphics compatibility issue or a residual cached setting.
Here are a few steps you can try to resolve this:
- Restart Teams: Fully quit the app (Cmd + Q) and reopen it to ensure changes are applied.
- Clear Teams Cache: 
- Delete the contents of the Backgrounds folder.
- Restart Teams and try selecting “None” again.
For official instructions on how to clear the team cache in Teams, please refer to this Microsoft support article: Clear the Teams client cache - Microsoft Teams | Microsoft Learn
- Check for Updates: Ensure Teams is updated to the latest version via Help > Check for Updates.
- System Compatibility: Some older Mac models may not fully support background removal features due to hardware limitations.
For official guidance on changing or removing backgrounds in Teams, please refer to Microsoft’s support article: Change your background in Microsoft Teams meetings - Microsoft Support
If the issue persists after trying these steps, please let us know your Mac model and Teams version so we can assist further.
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