I think I understand that you want the values in the text cells to change after a selection is made in the combo box.
If this is the case, use the EditingControlShowing event to setup the combo boxes change event.
private void dataGridView_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
if(dataGridView.CurrentCell.ColumnIndex == 1)
ComboBox cmb = (ComboBox)e.Control;
cmb.SelectedValueChanged += new EventHandler(cmb_SelectedValueChanged);
void cmb_SelectedValueChanged(object sender, EventArgs e)
Hope this helps