This question can't be answered for certain unless you can tell us what settings in the original document cause the header on page 1 to be different from the header on page 2.
- There could be one section (no section break) with the Different First Page option turned on in the Header & Footer Tools ribbon.
- Or there could be two sections, with a section break between pages 1 and 2, with or without the Different First Page option.
Since the first one is more likely, here's some code to try. You'll have to supply the path of the new image's file.
Sub ChangeHeaders()
Dim rg As Range
Dim pic As Shape
Dim lngTop As Long
Dim lngLeft As Long
Dim lngWidth As Long
With ActiveDocument.Sections(1)
.PageSetup.DifferentFirstPageHeaderFooter = False
With .Headers(wdHeaderFooterPrimary).Shapes(1)
Set rg = .Anchor
lngTop = .Top
lngLeft = .Left
lngWidth = .Width
.Delete
End With
Set pic = .Headers(wdHeaderFooterPrimary).Shapes.AddPicture( _
FileName:="D:\Pictures\XYZ.jpg", _
Left:=lngLeft, Top:=lngTop, Anchor:=rg)
With pic
.LockAspectRatio = msoTrue
.Width = lngWidth
End With
End With
End Sub