Nightingale has two modes for deciding where newly-inserted notes and rests belong relative to existing symbols.

   • When “Insert by Position” (found in the Notes/Rests menu) is not checked, if you insert the new note/rest at a horizontal position that’s very close to an existing note, rest, or chord on the same staff, the new note/rest is made into a chord with the existing note/rest/chord; otherwise it’s “moved to the left” as far as possible within the measure, based on the total duration of pre-existing notes/rests within the measure on the staff.  This is the way most other programs work.

   • When “Insert by Position” is checked, if you insert the new note/rest  at a horizontal position that’s very close to an existing note, rest, or chord on ANY staff, the new note is aligned with the existing one and played at the same time;  otherwise it goes between the two closest notes/rests.  This option is intended, for example, to let you fill in a melody, then just sketch in its accompaniment.