My coding

Private Sub Worksheet_Change(ByVal Target As Range)

'If Target.Column = 1 Or Target.Column = 2 Then

'if index don't exists, then pass in the last row index with last column index)


summary_row = Sheet1.Cells(Rows.Count, "a").End(xlUp).row
index_row = Sheet2.Cells(Rows.Count, "a").End(xlUp).row
lastCol = Sheet2.Cells(1, Columns.Count).End(xlToLeft).Column


i = indexCell(Target.row, summary_row, index_row)
MsgBox (i)
MsgBox (summary_row)
If i <> summary_row Then
MsgBox (i)
MsgBox (Target.row)
    Call FillCells(i, Target.row, lastCol)
Else
    Call FillCells(summary_row + 1, index_row, lastCol)
End If

'if index exists, then pass in pass in the existed row index with last column index)
'Call FillCells(existrow, lastCol)

'End If


End Sub

Public Function indexCell(ByVal selected_row As Integer, ByVal summary_lastrow As Integer, ByVal index_lastrow As Integer) As Integer

Dim j As Integer

    j = summary_lastrow
 
    For i = 1 To summary_lastrow
        If Sheet1.Cells(i, 1).Value = Sheet2.Cells(selected_row, 1).Value Then
            j = i
        End If
    Next i
     
    indexCell = j
 
End Function
Sub FillCells(ByVal summary_row As Integer, ByVal index_row As Integer, ByVal col As Integer)

   'this portion is to cater to insert new row.
 
   
        Sheet1.Cells(summary_row, 1).Value = Sheet2.Cells(index_row, 1).Value
     
        If Sheet2.Cells(index_row, 2).Value = "Priority 1" Then
           Sheet1.Cells(summary_row, 2).Value = "1"
        ElseIf Sheet2.Cells(index_row, 2).Value = "Priority 2" Then
           Sheet1.Cells(summary_row, 2).Value = "2"
        ElseIf Sheet2.Cells(index_row, 2).Value = "Priority 3" Then
           Sheet1.Cells(summary_row, 2).Value = "3"
        End If
       
        For i = 1 To col
        'MsgBox (Sheet2.Cells(1, i).Value)
            If Sheet2.Cells(1, i).Value = "first count" Then
                Sheet1.Cells(summary_row, 3).Value = Sheet2.Cells(index_row, i).Value
                MsgBox (Sheet2.Cells(index_row, i).Value)
            End If
        Next i
     
         For i = 1 To col
        'MsgBox (Sheet2.Cells(1, i).Value)
            If Sheet2.Cells(1, i).Value = "last count" Then
                Sheet1.Cells(summary_row, 4).Value = Sheet2.Cells(index_row, i).Value
            End If
        Next i
     
        If (Sheet1.Cells(summary_row, 4).Value <> "") Or (Sheet1.Cells(summary_row, 3).Value <> "") Then
        a = Sheet1.Cells(summary_row, 3).Value
        b = Sheet1.Cells(summary_row, 4).Value
        'c = (b - a) / a
            Sheet1.Cells(summary_row, 6).Value = FormatPercent(((a - b) / a), 2)
        End If
 
    'Cell(row, column)
 

End Sub