Zooming with a Scroll Wheel
If you have a mouse with a scroll wheel, you can use the scroll wheel to zoom in and out of tracks, both vertically and horizontally.
To continuously zoom horizontally using a scroll wheel:
Hold Option (Mac) or Alt (Windows) while turning the mouse scroll wheel.
To scroll the contents of the Edit window or Mix window horizontally:
1. Focus the window you want to scroll by clicking in it or bringing it forward.
2. Hold the Shift key while turning the mouse scroll wheel.