Missing symbols? drag LEFT (looser). Marking junk? drag RIGHT (stricter). Re-Detect after each change.
0 = auto. Increase if two marks land on one symbol; decrease if piles sit very close together.
Auto-set scans every sensitivity and parks the slider where the count is most stable. Review marks are near-matches just below your setting: click real missed piles in Add mode, reject junk in Erase mode, or resolve all at once.