Thanks for coming back, Lauren.
But there are many things mentioned in that link that are not connected with settings. The surface of your desk, mouse pad; try some alternatives. Then there is cleaning the sensor (use a cotton bud moistened (not wet) with an alcohol based cleaner or at a pinch, a rolled up wipe for spectacles.
Then there is signal interference. Have you changed the position of something recently. This is part of another Apple guide note.
Check for signal interference
Because Bluetooth works by transmitting signals through the air, some things can interfere with the wireless connection. Avoid situations in which metal objects come between the device and the computer. Don't put the computer under a metal desk or locked away behind a metal cabinet. Keep cordless phone base stations, microwave ovens, and other electrical devices that operate on a 2.4 GHz bandwidth away, and make sure that the wireless device and computer aren't more than 30 feet apart from each other.