Update Error Oledb C # [closed]

I can not use the UPDATE command more than once.

( link )

( link )

( link )

For example, when I perform the update at id 43, that's fine. But when I try to finish 44, it does not finish, but the 43 that gets the update ..

Code:

Int att, index;

Private void DataGrid_CellClick (object sender, DataGridViewCellEventsArgs and) {

   if(e.RowIndex >= 0)
   {

         Index = e.RowIndex;                                               
         att = Convert.ToInt32(DataGrid.Rows[Index].Cells[0].Value);

}
  } // when I click on a cell, Att receives the number that is // inside it, in case corresponding to ID in database tb. E index receives the index of the line.

private void Btnfnz_Click(objetc sender, EventArgs e)
{
     If(index >=0)
     {
          var linha = DataGrid1.Rows[index];
          cn.Connection = Conexão.conectar();
          cn.CommandText = "UPDATE Atendimento SET HorarioOut = ' " + Txthr.Text + " ' WHERE ID=@att";
          cn.Parameters.AddWithValue("@att",att);
          cn.ExecuteNonQuery();
          cn.Connection = Conexão.desconectar();
     }
     else 
     {
           MessageBox.Show("Lista vazia!");
     }
     Refreshatt(); //Carrega o datagrid com dados do banco dados, onde horarioOut estiver em branco.
}

Everything works fine, but when I try to do a new update, it even does, however in the msm ID, it is fixed in the first ID I made the update.