Private Sub Form_Load()
Dim sValue As String
 
  sValue = "hallo"
  sValue = ReplaceA(sValue, "a", "q")
  Debug.Print sValue
  sValue = ReplaceA(sValue, "l", "z")
  Debug.Print sValue
 
End Sub
 
 
Private Function ReplaceA(ByVal sValue As String, ByVal sSearch As String, _
  ByVal sReplace As String) As String
Dim i           As Integer
 
  For i = 1 To Len(sValue)
    If Mid(sValue, i, 1) = sSearch Then
      Mid(sValue, i, 1) = sReplace
    End If
  Next i
  ReplaceA = sValue
 
End Function