It looks like on your update form you do not have the values already in the db bound to the corresponding form elements. To fix this you need to make sure that you have a recordset on the page that is being filtered by the records id.
Once the recordset is on the page you need to select the form element, then go to the bindings tab and expand the entry for your recordset. In here select the column that corresponds to the form field then click the bind button.
Once you have bound the default values to the form fields it should then retain whatever values you have for that record.