View Unlocking Segments
If you wish to unlock a single segment if it been locked, right click on the segment and from the drop down select unlock.
Watch Video: Unlocking a Segment from a specific area
If you have multiple segments locked, you can use the auto-selection tool to unlock them.
In order to do this you must preserve the shaded area that the auto-selection has created.
Once you create the shaded area using the auto-selection tool, before releasing the left mouse button click the right button. The shaded area will now be maintained. If you right click the mouse within this area a context menu will appear.
In the drop down menu select Unlock All. All the segments that were locked will now be unlocked.