Sub ChangeLineColor()

  Dim sld As Slide, shp As Shape, GrayColor(1 To 3) As Long, Arr As Byte
  Dim CheckColor As Long
  
    'Set GrayColors
    GrayColor(1) = 10921638
    GrayColor(2) = 12287562
    GrayColor(3) = 12566463
  

    For Each sld In ActivePresentation.Slides
      sld.Select 'not necessary but fun to watch
      Debug.Print sld.SlideIndex 'again not necessary but useful if errors
        For Each shp In sld.Shapes
          If shp.Type <> msoGroup Then
            shp.Select 'not necessary but fun to watch
            CheckColor = shp.Line.ForeColor.RGB
            For Arr = 1 To 3
              If GrayColor(Arr) = CheckColor Then
                shp.Line.ForeColor.RGB = 12287562 'Change to blue
              End If
            Next Arr     
          End If
        Next shp
      Next sld
  MsgBox "done"

End Sub