Oh my goodness. That is something we learned in Home Ec class back in high school. When? well, about 1949! And I know schools no longer teach Home Economics!
Since the presser foot automatically causes the tension discs to close, there is tension on the thread. In order to pull the thread through the needle with out having it hang up and feel "tight" the pressure must be released. Thus, the presser foot should be in the "up" or "pressure off" position.
Old timers do remember some of the good lessons they learned.