The trouble is you're confusing the positions of scales with the positions on the neck.

The positions of the G major scale would be called the 1st position, 2nd, and so on.

On the other hand, a position on the neck is the fret below your middle finger. So G major played 3nps from the 3rd fret 6th string is in the 4th position, but it's the FIRST position of the SCALE.