Hi Cyrax2988,
Thank you for posting in Microsoft Community.
While using multiple monitors in Extended mode, the apps can be moved to other monitors. Based on your description on using Magnifier, one of the workarounds you can perform is to use Docked View or Lens View options in Magnifier.
To do this, Open Magnifier,
- To use the docked view, press Ctrl+ Alt+ D.
- To use the lens view, press Ctrl+ Alt+ L.
For more features on Magnifier, you may refer Using Magnifier on Windows 10
This seems to be a good feature suggestion. I would suggest you to make use of the Feedback Hub, where you can send suggestions and ideas to help us improve your Windows experience.