Editing : Edit Modes and Tools : Edit/Tool Mode Keyboard Lock

Edit/Tool Mode Keyboard Lock
Enable Options > Edit/Tool Mode Keyboard Lock to lock the currently selected Edit Tools (Zoom, Trim, Grabber, and Pencil only) in place and prevent them from being inadvertently changed when using keyboard shortcuts. However, even when Edit/Tool Mode Keyboard Lock is enabled, Edit Tool types can still be changed using the mouse or by using the Right-click menu. You can also switch between tools (such as switching from the Grabber to the Trim) using keyboard shortcuts.
To lock (or unlock) the current Edit Tool modes:
1 Select the Edit Tool modes you want (such as the Standard Trim tool, Time Grabber tool, and the Free Hand Pencil tool).
2 Select (or deselect) Options > Edit/Tool Mode Keyboard Lock.