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R37, R38, and RV1 set the contrast of the LCD. You'll notice that R37 is so really far away from the other two resistors to reduce the length of the trace that has to be run.resistors. This is for practical reasons. This circuit runs all the way across the board so R37 is literally just somewhere along the way where it would fit. Not every design choice is a pretty one. 
INSERT DIAGRAM HIGHLIGHTING TRACES AND HOW THEY TRAVERSE THE BOARD
INSERT DIAGRAM OF CONTRAST KNOB
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