Try the following. It adds your watermark to each header in the first Section of the document. I don't know what the 'PowerPlusWaterMarkObject325783140' watermark is, so I can't test with that. Neither can I test the code with your numerous other variables. You'll note I've used a different naming convention for the watermarks, as they can't all have the same name.
Code:
Dim Shp As appWord.Shape, HdFt As appWord.HeaderFooter
Set Doc = appWord.Documents.Add.Open(NewDoc, , False, False)
With Doc
'Add the watermark to each header in the first Section
With .Sections.First
For Each HdFt In .Headers
Set Shp = HdFt.Shapes.AddTextEffect(PowerPlusWaterMarkObject325783140, _
FileType, "Arial Narrow", 38, False, False, 0, 0)
With Shp
.Name = "PowerPlusWaterMarkObject" & Format(Now, "YYMMDD") & Format(HdFt.Index, "00")
.TextEffect.NormalizedHeight = False
.Line.Visible = False
.Fill.Visible = True
.Fill.Solid
.Fill.ForeColor.RGB = RGB(192, 192, 192)
.Fill.Transparency = 0.5
.Rotation = 315
.LockAspectRatio = True
.Height = InchesToPoints(3.29)
.Width = InchesToPoints(6.85)
.WrapFormat.AllowOverlap = True
.WrapFormat.Side = wdWrapNone
.Left = appWord.InchesToPoints(-0.5)
.WrapFormat.Type = 3
.RelativeHorizontalPosition = wdRelativeVerticalPositionMargin
.RelativeVerticalPosition = wdRelativeVerticalPositionMargin
.Top = InchesToPoints(3)
End With
.Range.FormattedText.ShowAll = False
Next
End With
With .ActiveWindow.View
.ShowMarkupAreaHighlight = False
.ShowComments = False
.ShowRevisionsAndComments = False
End With
.FormattingShowClear = True
'Save Document as PDF
.SaveAs FileName:=NewFName, FileFormat:=wdFormatPDF
'Close application and document
.Close False
End With
appWord.Quit
Set Shp = Nothing: Set Doc = Nothing: Set appWord = Nothing