High bar/Low bar squats

The high bar squat is simpler to execute and can be performed by beginners or athletes without worrying about intensive movement instruction or excessive lumbar spine flexion. A low bar position isn't difficult to execute but will take a little more time for an athlete to dial in and feel comfortable. 

The correct position is the one that best serves your training goals and leads to the adaptations you are seeking.   I suggest having a trainer show you the proper form.  If they aren't done correctly there is potential for injury.   As you can see from the diagram, they are similar, but have specific differences that a trainer can properly show you.