如何保存对DataGridView所做的更改

我以为我知道怎么做这个，但是当我真正去做的时候，似乎我不知道怎么做。

我想要实现的是显示一个表的过滤行，是在数据集当搜索btn被点击。允许用户在datagridview上进行更改，或者在单击update btn时，使用更新面板上的文本框提供的值更新所选行。但我似乎做不到。

 private void Display()
    {
        bindingSourceDisplay.DataSource=_dsNorthwind.Customers.Where(x=>!x.IsRegionNull()                         && !x.IsFaxNull()                                                                         && !x.IsPostalCodeNull()).Take(10);
        dgvSearchResult.DataSource = bindingSourceDisplay;
    }
 internal void UpdateSelectedRows(UpdateBtnClickedEventArgs e)
    {
        //cannot do this because datagridviewselectedrow and customerrow are a type mismatch
        foreach (DS_Northwind.CustomersRow selectedRow in dgvSearchResult.SelectedRows)
        {
            selectedRow.Phone = e.PhoneNum;
            selectedRow.PostalCode = e.PostalCode;
        }
//how do I update each selected rows in datagridview? Can't do selectedRow.Cells["ColName"] either for some reason...
//if my dataset is connected to my database, isn't saving changes as simple as doing accept changes?
            _dsNorthwind.AcceptChanges();
        }