Rearrange items by dragging one or more at a time within (or between) lightboxes.
Hold down the Apple Key and click to select individual images, or use the Shift key select a range of multiple images Hold down the Ctrl key and click to select individual images, or use the Shift key to select a range of multiple images

Save
Exit Arranger

To copy (rather than move) items between lightboxes, press and hold Apple Key while dragging. To copy (rather than move) items between lightboxes, press and hold Ctrl key while dragging.