Hello cat burlow,

Thank you for using Apple Support Communities. 

I see that your Magic Mouse isn't tracking when you use it. Take a look at the following from the If your Apple wireless mouse, keyboard, or trackpad aren‘t working as expected support article:

Your mouse or trackpad doesn't track as expected

Apple Wireless Mouse, Magic Mouse, and Magic Mouse 2 can be used on most smooth surfaces; however, if tracking issues occur, try these options:

• Choose System Preferences from the Apple menu, then choose Mouse. Set the Tracking slider to adjust how fast the pointer moves as you move the mouse.
• Try using a different surface to see if the tracking improves.
• Turn the mouse over and inspect the sensor window. Use compressed air to gently clean the sensor window if dust or debris is present.
• If multiple Bluetooth wireless devices are in use nearby, try turning them off one at a time to see if the issue improves. Bandwidth intensive devices could affect tracking.

Learn more about what to do if your trackpad isn't tracking correctly.

Best regards.