IncrementOffsetX Method
Changes the horizontal offset of the shadow by the specified number of points. Use the OffsetX property to set the absolute horizontal shadow offset.
expression.IncrementOffsetX(Increment)
expression Required. An expression that returns a ShadowFormat object.
Increment Required Single. Specifies how far the shadow offset is to be moved horizontally, in points. A positive value moves the shadow to the right; a negative value moves it to the left.
Example
This example moves the shadow for shape three on myDocument to the left by 3 points.
Set myDocument = ActivePresentation.Slides(1)
myDocument.Shapes(3).Shadow.IncrementOffsetX -3