expression.SetDefaultChart(FormatName, Gallery)
expression Required. An expression that returns one of the objects in the Applies To list.
FormatName Optional Variant. The name of the specified custom autoformat. This name can be a string that denotes the custom autoformat, or it can be the special constant xlBuiltIn to specify the built-in chart template.
Gallery Optional Variant.
Example
This example sets the default chart template to the custom autoformat named "Monthly Sales."
myChart.Application.SetDefaultChart FormatName:="Monthly Sales"