VBA Excel: code pour fonction somme à étendre

Sub Totaux()
Dim dercol As Long
Dim derlig As Long
Dim wk As Workbook
Dim ws As Worksheet
Dim i As Long
Dim j As Long

    Set wk = ThisWorkbook     '--- A adapter
    Set ws = wk.Worksheets(1)     '--- A adapter
    
    dercol = ws.Range("A1").End(xlToRight).Column
    derlig = ws.Range("A" & Rows.Count).End(xlUp).Row
    
    For i = 2 To dercol
        For j = 3 To derlig
            ws.Cells(2, i).Value = ws.Cells(2, i).Value + ws.Cells(j, i).Value
        Next j
    Next i
    
    ws.Range(ws.Cells(2, 2), ws.Cells(2, dercol)).Font.Bold = True

    Set wk = Nothing
    Set ws = Nothing
    
End Sub