Drone Drifting in One Direction

That could be a problem with one of the motors or propellers. It could be that one of the motors is just a little more or less efficient than the others or that one has a little something wrapped around it. Either way it can probably be fixed by adjusting the trim settings with the trim button on the back of the motor. You can use the troubleshooting page to see how to do that. If that doesn't fix it then try checking for debris wrapped around the shaft of the motor or around the propeller. The troubleshooting guide can help you with that too. Good luck!