Create a procedure to change all the page fields. This one loops through all the worksheets in the workbook and if the worksheet has a pivot table, it changes the page field to match the page field on the pivot table passed to the sub.
Sub ChangePage(pt As PivotTable)
Dim strPageValue As String
Dim wks As Worksheet
Dim ptUpdate As PivotTable
Application.ScreenUpdating = False
Application.EnableEvents = False
strPageValue = pt.PivotFields("Area").CurrentPage
For Each wks In ThisWorkbook.Worksheets
On Error Resume Next
Set ptUpdate = wks.PivotTables(1)
If Err.Number = 0 Then
On Error GoTo 0
wks.PivotTables(1).PivotFields("Area").ClearAllFilters
wks.PivotTables(1).PivotFields("Area").CurrentPage = strPageValue
End If
Err.Clear
Next wks
Application.ScreenUpdating = True
Application.EnableEvents = True
End Sub
Then place a call to this procedure in the worksheet code itself and pass the pivot table you changed:
Private Sub Worksheet_PivotTableUpdate(ByVal Target As PivotTable)
Call ChangePage(Target)
End Sub
Change the name of the pivot field from "Area" to the page field you need, for example "US_Region".
This may not be suitable if people are frequently changing the structure of your pivot tables in other ways, as it will trigger each time the pivot table is changed, including when it is refreshed. It will also give an error if users remove the specified page field.
If the pivot tables are static though, this might do.