Using excel VBA to change format of headers/footers date and time in powerpoint

Question

I currently have the following set up. Everything is working fine, except .DateAndTime.Format is not changing the date format in the bottom left hand corner of the slide. The date is visible as 4/10/2020, but I can't get it to change to April 10, 2020 using the below:

  Set PowerPointApp = GetObject(class:="PowerPoint.Application")
  Set myPresentation = PowerPointApp.Presentations.Add
    myPresentation.ApplyTemplate "[template file here]"
  Const ppSlideSizeA4Paper = 2
    myPresentation.PageSetup.SlideSize = ppSlideSizeA4Paper
  With myPresentation.SlideMaster.HeadersFooters

    .SlideNumber.Visible = True
    .DateAndTime.Visible = True
    .DateAndTime.UseFormat = True
    .DateAndTime.Format = ppDateTimeMMMMdyyyy

  End With

Answer 1

I think you found a bug, because VBA won't change the date format on a master or its child layouts. It's possible to set on the slides:

Sub DateTime()
    Dim oSlide As Slide
    For Each oSlide In ActivePresentation.Slides
        With oSlide.HeadersFooters
            .SlideNumber.Visible = True
            With .DateAndTime
                .Format = ppDateTimeMMMMdyyyy
                .Visible = msoTrue
            End With
        End With
    Next oSlide
End Sub

However, when you insert a new slide, the date will still reflect the format set on the layout and you'll have to rerun the macro.