Choose Options > Snapping > Enable to turn automatic snapping on or off.
Snapping helps you position the cursor, make selections, and align items along the grid when you paste, mix, trim, or work with markers and regions. As you drag items in the editor, snap points are highlighted.
Hold the Shift key to temporarily suspend snapping.
Choose Options > Snapping > Enable to turn automatic snapping on or off. When snapping is enabled, objects will snap to the following points:
The cursor
Time selection edges
You can also choose to snap events to grid divisions, markers, or events.
When snapping is enabled, you can also choose to have objects snap to whole time divisions as designated by the marks on the time ruler above the editor.
Choose Options > Snapping > Grid to toggle snapping to grid lines.
To change the time format of the grid, choose Options > Status Format and then choose a setting from the submenu (or Control-click the time ruler and choose a format from the shortcut menu).
When snapping is enabled, you can also choose to have elements in the editor snap to markers.
Choose Options > Snapping > Markers to toggle snapping to markers and regions.
For more information, see "Working with markers and regions."
When snapping is enabled, you can also choose to have elements in the editor snap to event boundaries.
Choose Options > Snapping > Events to toggle snapping to event boundaries.
For more information, see "Event-based editing."
When snapping is enabled, you can also choose to have elements in the editor snap to zero-crossings.
Choose Options > Snapping > Zero Crossings to toggle automatic snapping to zero crossings.
If you want to manually adjust a selection to zero-crossing points, you can choose Edit > Selection > Snap to Next Zero and Edit > Selection > Snap Edge to Next Zero.
For more information, see "Selecting data using the mouse."