Hi Sarah Threlfall,
Welcome to Microsoft Q&A!
I'm sorry to hear of the unwanted mismatch between your Surface Laptop 7 and Ultrawide monitor, especially when it's a new device and the display worked with your old Surface Book.
I can see that you already tried most possible solutions, still, I want to check everything one more time just to make sure. Re-confirm your setup is correct following this guide: Supported external display resolution and refresh rates for Surface - Microsoft Support
- Remember to choose the right display before making changes
- Refresh rate: 60 Hz (in Settings > Display > Advanced display)
- Try setting the same rate for both your laptop and monitor
- You can lower the refresh rate of the Ultraview to test its behavior
- Resolution: choose the Recommended option
- Or check with each resolution if needed.
- Set correct aspect ratio for your monitor:
- Choose 21:9 as 3440 x 1440 previously worked
- If there's a Reset Display option, select it
- Disable Zoom or Fit to Screen (if any)
If the issue still persists after trying everything, it'd be helpful if you can share the connector you're using. Because based some reports from other users with similar problems, DisplayPort might be better for output than HDMI. So, if you're using a HDMI cable, consider checking out other 60Hz supported DisplayPort connectors.
We look forward to hearing from you and reviewing the information. Thank you for your time.
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