I had the same question.
Setting "ActiveWindow.View.DisplayPageBoundaries = False" in AutoOpen() works and sticks if you open a document from within Word (when the Word App is already loaded). It works for a few seconds but does NOT stick, as you point out, ... if Word is spawned by the OS when you double-click on a Word Doc and the Word App isn't previously loaded.
It appears to me that Word resets this attribute after it closes out AutoOpen. Here is an inelegant workaround: schedule another Macro to set this attribute a couple of seconds after AutoOpen closes:
Sub AutoOpen()
Dim ScheduledTime As Double
Dim SpawnedSub As String
ScheduledTime = Now + TimeSerial(0, 0, 2)
SpawnedSub = "TurnOffDisplayPageBoundaries"
Application.OnTime ScheduledTime, SpawnedSub
End Sub
Public Sub TurnOffDisplayPageBoundaries()
' Hide white space between pages by default.
With ActiveWindow.View
.Type = wdPrintView
.DisplayPageBoundaries = False
End With
Application.ScreenUpdating = True
End Sub