windows forms datagrid view combo box is loosing its selection on selecting other row

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C#

Windows

DataGridView

DataGrid

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Need urgent help here
I have a data grid showing company name and filters in drop down
/* filters in drop down are according to company name in that row *\

//for binding list to combo box on its click

private void dgvJournalEntries_EditingControlShowing(object sender, DataGridViewEditingControlShowingEventArgs e)
        {
            //selection of combo box
            List<UDT.MgmtJournalEntryEnterprise> LstCompanyFiltersGrdOpr =       this.bsEnterpriseCompanyFIlter.DataSource as List<UDT.MgmtJournalEntryEnterprise>;
            if (dgvJournalEntries.Columns[dgvJournalEntries.CurrentCell.ColumnIndex].Name == "CompanyFilters")
            {
                ComboBox combo = e.Control as ComboBox;
                if (combo != null)
                {
                    // Remove an existing event-handler, if present, to avoid  
                    // adding multiple handlers when the editing control is reused.
                    combo.DropDown -= new EventHandler(combo_DropDown);
                    // Add the event handler. 
                    combo.DropDown += new EventHandler(combo_DropDown);
                }
            }
        }
//And for Binding List
  void combo_DropDown(object sender, EventArgs e)
        {
            List<UDT.MgmtJournalEntryEnterprise> LstCompanyFiltersGrdOpr = this.bsEnterpriseCompanyFIlter.DataSource as List<UDT.MgmtJournalEntryEnterprise>;
            ComboBox combo = sender as ComboBox;
            combo.BeginUpdate();
            int currentColIndex = dgvJournalEntries.CurrentCell.ColumnIndex;
            int currentRowIndex = dgvJournalEntries.CurrentCell.RowIndex;
            string preColumnCompanyValue = dgvJournalEntries[currentColIndex - 1, currentRowIndex].Value.ToString();
            var CompanyFilterList = LstCompanyFiltersGrdOpr.Where(X => X.CompanyName == preColumnCompanyValue).SelectMany(X => X.tEDJFilterList).ToList();
            if (CompanyFilterList.Count() > 0)
            {
                combo.DataSource = CompanyFilterList.Select(C => C.FName).ToList();
            }
            combo.EndUpdate();
        }

But the issue is after selecting a value in from drop down when i click on any other cell or row , previous drop down lost its selected value