Target=active cell plus 17 ?

Private Sub Worksheet_Change(ByVal Target As Range)
Dim sUser As String
Dim rZelle As Range
ActiveSheet.Unprotect
'angemeldeter Username
sUser = Environ$("USERNAME")
'Zelle
Set rZelle = ActiveSheet.Range(Target.Row, 17)
'Sverweisformel
With rZelle
.Formula = "=VLookup(" & sUser & "," & _
"'Z:\Ordnerpfad!K5:N200, 2, False) & "","" & "" "" & VLookup(" & sUser & "," & _
"'Z:\Ordnerpfad!K5:N200, 3, False)"
.Formula = .Value & " Stelle " & Date
End With
ActiveSheet.Protect, userinterfaceonly:=True
ActiveSheet.EnableAutoFilter = True
End Sub

Private Sub Worksheet_SelectionChange(ByVal Target As Range)

If UserForm1.Visible = True Then UserForm1.TextBox1.Text = ActiveSheet.Range(Target.Row, 17). _

Value

End Sub