' Procedure to Generate Pie Chart
Private Sub fn_generate_pie_graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlPie
   Next cht
End Sub

' Procedure to Generate Bar Graph
Private Sub fn_Generate_Bar_Graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlBar
   Next cht
End Sub

' Procedure to Generate Column Graph
Private Sub fn_generate_column_graph_Click()
   Dim cht As ChartObject
   For Each cht In Worksheets(1).ChartObjects
      cht.Chart.Type = xlColumn
   Next cht
End Sub