Sub DetectMax()
Dim nb_ligne As Integer, last_col As Integer
nb_ligne = Application.WorksheetFunction.CountA(Range("B:B")) '20
last_col = Application.WorksheetFunction.CountA(Range("1:1")) '10
Range("B1", Cells(20, 10)).Font.Bold = False
For l = 1 To nb_ligne
For c = 1 To last_col
If Cells(l, c) = Application.WorksheetFunction.Max(Range(Cells(l, 2), Cells(l, last_col))) Then
Cells(l, c).Font.Bold = True
End If
Next c
Next l
End Sub