Drift so much in Altitude Hold mode and rotate yaw by itself

Hello guys Now I’m setting up the big quadrotor drone. With the orange cube flight controller, here 3 gps with ardupilot. Here I’ve some problems. My drone drifts so much in Altitude Hold Mode that it’s not stable anymore. And when I lift the drone in the air, the drone rotate YAW by itself without doing anything. Since I turned on the drone’s battery, the raw degree is no longer at 0 degrees, but at about 70 degrees. Any suggestion on how to fix these problems?

Not w/o seeing a .bin flight log. Post a link to one.

Besides the log. If your drift goes the same direction it could be a hardware issue like a bent arm or a bad level of your flight controller.