Sub Worksheet_Change(ByVal Target As Range)
    Integrality.Format_Entries (Target(1))
End Sub
===================================
Public Sub Format_Entries(oRng As Range)
  'Nałożenie reguł poprawności wprowadzenia numeru
  Select Case oRng.Address(0, 0)
  Case "A34", "A35", "A36", "A37", "A38", "A39"
    Application.EnableEvents = False
    With oRng
      If (Len(.Value) <> 8) Or (Not IsNumeric(.Value)) Or _
         .Value = "" Then
        .Select
        MsgBox "Wprowadź poprawny numer rachunku (8 cyfr)."
        .ClearContents
      Else
        .NumberFormat = "#### ####"
      End If
    End With
    Application.EnableEvents = True
  End Select
End Sub

Sub Worksheet_Change(ByVal Target As Range)
    Integrality.Format_Entries Target.Address ' tu zmiana
End Sub

Public Sub Format_Entries(adrAdres As String)  ' tu zmiana
    
Select Case adrAdres ' tu zmiana

'Nałożenie reguł poprawności wprowadzenia numeru
Case "$A$34", "$A$35", "$A$36", "$A$37", "$A$38", "$A$39"
On Error GoTo InvalidEntry
Application.EnableEvents = False
    With ActiveCell
        If Len(.Value) <> 8 Or IsNumeric(.Value) = False Then
            Err.Raise 0
        Else: .NumberFormat = "#### ####"
        End If
    End With
Application.EnableEvents = True
Exit Sub
InvalidEntry:
    MsgBox "Wprowadź poprawny numer rachunku (8 cyfr)."
    Range(adrAdres).Activate ' tu zmiana
Application.EnableEvents = True

End Select

End Sub

Sub Worksheet_Change(ByVal Target As Range)
    Integrality.Format_Entries
End Sub

Public Sub Format_Entries()
    
Select Case ActiveCell.Address

'Nałożenie reguł poprawności wprowadzenia numeru
Case "$A$34", "$A$35", "$A$36", "$A$37", "$A$38", "$A$39"
On Error GoTo InvalidEntry
Application.EnableEvents = False
    With ActiveCell
        If Len(.Value) <> 8 Or IsNumeric(.Value) = False Then
            Err.Raise 0
        Else: .NumberFormat = "#### ####"
        End If
    End With
Application.EnableEvents = True
Exit Sub
InvalidEntry:
    MsgBox "Wprowadź poprawny numer rachunku (8 cyfr)."
    ActiveCell.Value = Null
Application.EnableEvents = True

End Select

End Sub