vba to updata data from one sheet to another

Hi all,

I have the below code which I am trying to use to update data from one sheet to another. The problem is that the location of the relevant columns in the destination file is dynamic and changes (though the name remains the same).

Could we find something which can remove the restriction of the below colored columns. These columns may not necessarily be in location provided in the code.

Thanks.

Sub myUpdate()

     'The name of the input worksheet.
     inputSheet = "Source File"
     'The name of the output worksheet.
     outputSheet = "Destination File"

     PO_Number_Column_inputSheet = "A"
     Part_Number_Column_inputSheet = "B"
     Status_Column_inputSheet = "C"
     Quantity_Column_inputSheet = "D"

     PO_Number_Column_outputSheet = "B"
     Part_Number_Column_outputSheet = "E"
     Status_Column_outputSheet = "AA"
     Quantity_Column_outputSheet = "AC"

     'The first row with data in it, not including headers, in the input worksheet.
     firstRow_inputSheet = 2
     'The last row with data is found using the PO Number column A in the input sheet.
     lastRow_inputSheet = Sheets(inputSheet).Range(PO_Number_Column_inputSheet & Rows.Count).End(xlUp).Row

     'The first row with data in it, not including headers, in the output worksheet.
     firstRow_outputSheet = 2
     'The last row with data is found using the PO Number column B in the output sheet.
     lastRow_outputSheet = Sheets(outputSheet).Range(PO_Number_Column_outputSheet & Rows.Count).End(xlUp).Row
     
     R_input = firstRow_inputSheet

     Do Until R_input > lastRow_inputSheet

          PO_Number_Value_inputSheet = Sheets(inputSheet).Range(PO_Number_Column_inputSheet & R_input).Value
          Part_Number_Value_inputSheet = Sheets(inputSheet).Range(Part_Number_Column_inputSheet & R_input).Value
          Status_Value_inputSheet = Sheets(inputSheet).Range(Status_Column_inputSheet & R_input).Value
          Quantity_Value_inputSheet = Sheets(inputSheet).Range(Quantity_Column_inputSheet & R_input).Value

          R_output = firstRow_outputSheet

          Do Until R_output > lastRow_outputSheet
               
               PO_Number_Value_outputSheet = Sheets(outputSheet).Range(PO_Number_Column_outputSheet & R_output).Value
               Part_Number_Value_outputSheet = Sheets(outputSheet).Range(Part_Number_Column_outputSheet & R_output).Value
               
               If PO_Number_Value_inputSheet = PO_Number_Value_outputSheet _
               And Part_Number_Value_inputSheet = Part_Number_Value_outputSheet Then
                    Sheets(outputSheet).Range(Status_Column_outputSheet & R_output).Value = Status_Value_inputSheet
                    Sheets(outputSheet).Range(Quantity_Column_outputSheet & R_output).Value = Quantity_Value_inputSheet

                    Exit Do
               End If

               R_output = R_output + 1
          Loop
          R_input = R_input + 1
     Loop
End Sub