Music Tech Help Guy walks through quantizing whole-note chords in Logic Pro's Piano Roll editor, using the Time Quantize menu to snap notes that don't land on the bar line.
The key insight: quantization value isn't tied to the MIDI region, it's applied per note. Each note in a chord or phrase can carry its own quantize setting depending on where it falls on the grid.
He shows how to select a value like a whole note or half note, drag over specific notes, and hit Q to quantize just those. De-quantizing with option-command-Q (or a quick command-Z) resets things if you want to start over.
Understanding this note-by-note behavior clears up a common beginner confusion and gives you finer control when cleaning up chords, basslines, or melodies that don't fall on neat rhythmic boundaries.