Position items using alignment guides
Alignment guides appear when the edges of a region you are moving align with another region in the timeline and when automation points you are moving align with other items in the timeline. Alignment guides briefly appear as the edge of the region or automation point aligns with other items in the timeline.
You can turn alignment guides on or off in the Snap pop-up menu.
Turn alignment guides on or off
Choose Snap > Alignment Guides in the Tracks area menu bar.