In Back to the Future 2, old Biff stole the time machine in 2015 and went back in time to give an Almanac to young Biff. This journey was successful.
The Time Machine wasn't a common thing found on every crossing. So how was he able to operate it? Driving a flying car could be easy, but what about Time Circuits and required speed? I don't think there was a quick start manual inside the time machine. Even a genius could be confused and feared with consequences of wrong operation. But that's not the case of old Biff.
Do you have an explanation?