For the app. Clear the cache. Uninstall and reinstall if needs be.
For the desktop. The only way to be sure that it's not you is to verify that you're not experiencing problems on/in any other program. An easy way to isolate this is from a PE (Windows or Linux). Erratic mouse moves. Touchscreen maybe? Interference between wireless devices - keyboard/mouse? Does it happen on another device?
Knowing the solution doesn't mean knowing the method. Yet answering correctly and regurgitation are considered "learning" and "knowledge".