Dim slide As slide
Dim shape As shape

For Each slide In ActivePresentation.Slides
    For Each shape In slide.Shapes
        If shape.TextFrame.HasText Then
            If shape.HasTextFrame Then
                shape.TextFrame.TextRange.Text = Replace(shape.TextFrame.TextRange.Text, "PM3", "TCF6203")
            End If
        End If
    Next shape
Next slide
End Sub