Word macro that sets Different First Page = true

[Rzv]

I am really new to VBA and I am trying to make a macro that sets the header different first page to true, I am planning to use word batch processor's user-defined mode to make it work folder-wide but I cannot make it work
English is not my first language so sorry if I "talk" weird

This is my latest try, it works but only for singular documents, not batch

Sub HeaderFirstPage()
Let ActiveDocument.Sections(1).PageSetup.DifferentFirs tPageHeaderFooter = True
End Sub