expression.UseSystemSeparators
expression Required. An expression that returns one of the objects in the Applies To list.
Example
In this example, "1,234,567.89" is placed in cell A1. The system separators are then changed to dashes for the decimals and thousands separators.
Sub ChangeSystemSeparators()
Range("A1").Formula = "1,234,567.89"
MsgBox "The system separators will now change."
' Define separators and apply.
Application.DecimalSeparator = "-"
Application.ThousandsSeparator = "-"
Application.UseSystemSeparators = False
End Sub