I also have had difficulty memorizing musicin my 50 plus years of playing.
I have difficulty memorizing a piano score with 2 staves, then you had a
pedal staff for the organ, and just forget it.  I have to use a score to
feel comfortable at the keyboard.  Now this is just for keyboard music.
What about the conductors who have to memorize an entire orchestral score,
but perhaps for them the score just gets in the way.  I sit at a
performance in awe of the conductor sans score.  Add an opus with a chorus
and still performing without score, I just get blown away.  How do they do
it?

Tom Warren