In Logic Pro, do one of the following:
Shift-click in the waveform display to move the start or end point.
Press and hold Shift as you drag the start or end point of the selected area in the waveform display.
Using either method, the proximity of your click—to the start or end of the selected area—determines whether you change the start or end point boundary. The closest one wins.
Tip: If you press and hold Option-Shift, the more distant selection boundary is changed (rather than the nearer).
You can move the whole selection to the left or right without changing its length.
Option-click the selection.
Click the selection with the Move tool.
Drag left or right.
When you move the selected area, the pointer or Move tool turns into a two-headed arrow.