You shouldn't need to 'seek' either the header or document views. You may also need to specify which header to update. Try:
Code:
While ActualCopies <= mCopies
If ActualCopies = 1 Then
With ActiveDocument.Sections.First.Headers(wdHeaderFooterPrimary).Range
.Text = "Customer Copy"
.Paragraphs.First.Alignment = wdAlignParagraphCenter
End With
etc.