Back to 4-thread settings

OH NO.... now how do I go back?   I'm drunk with pride after my success with the coverstitch and chainstitch. so I want to go back to the original settings.  Should be a breeze, no?  NO!   I can't figure out how I threaded the lower looper!   I understand where the thread has to go, but I had to remove the throat plate and the presser foot, plus guide the thread through the little hole from back to front with a # 9 steel crochet hook.  I'm sure that's NOT how I threaded it before.  Minna, Georgie, Nancy... I need you!
But I did get it threaded in my own way, so I forge ahead and try that 3-thread flatlock with the multi-purpose foot.  After several  attempts that looked awful, I finally get a nice neat flatlock.  And I even put it to good use on a pair of undies whose (chinese) factory flatlock stitching missed one side of the elastic in several places.