Tweak Times Dialog
Utility|Tweak Times
Lets you modify all time values of markers, captions and/or cue points.

Modify time values
The amount of time in milliseconds to be added/subtracted.
Select the action here.
Apply to
You need to select at least one of the items.
Click OK to execute the action. A confirmation dialog will be displayed if some markers/captions/cue points will have to be deleted.
This action cannot be undone.