How do I autofill dropdown field values

<div class="col-md-10" data-select2-id="34">
                            <select class="form-control select2-hidden-accessible" name="PrimarySponser.SponserInsurerID" id="PrimarySponser_SponserInsurerID" style="width: 100%" data-select2-id="PrimarySponser_SponserInsurerID" tabindex="-1" aria-hidden="true">
                            </select>
                    </div>

<div class="col-md-10" data-select2-id="34">
    <select class="form-control select2-hidden-accessible" name="PrimarySponser.SponserInsurerID" id="PrimarySponser_SponserInsurerID" style="width: 100%" data-select2-id="PrimarySponser_SponserInsurerID" tabindex="-1" aria-hidden="true">

<option value="9" data-select2-id="42">
Funded Mandates administration
</option>
</select>

var PrimarySponser_PatientSponserID = 0;
    var SecondarySponser_PatientSponserID = 0;

    fnFillSponserInfo();

    function fnFillSponserInfo(){
        if (PrimarySponser_PatientSponserID > 0)
        {
            var primaryPayer = new Option('', 0, false, false);
            $('#PrimarySponser_SponserInsurerID').append(primaryPayer).trigger('change');

            var primaryNetwork = new Option('',  0, false, false);
            $('#PrimarySponser_PayerNetworkID').append(primaryNetwork).trigger('change');

            var primaryPackage = new Option('',  0, false, false);
            $('#PrimarySponser_SponserPackageID').append(primaryPackage).trigger('change');
        }

    }


    $('#PrimarySponser_SponserInsurerID').select2({
        ajax: {
            url: '/Search/Payers',
            data: function (params) {
                var query = {
                    term: params.term
                }
                // Query parameters will be ?search=[term]&type=public
                return query;
            },
            processResults: function (data) {
                // Tranforms the top-level key of the response object from 'items' to 'results'
                return {
                    results: data.items
                };
            }
        },
        minimumInputLength: 3, placeholder: 'Select a payer'
    });

    $('#PrimarySponser_PayerNetworkID').select2({
        placeholder: 'Select a network'
    });

    $('#PrimarySponser_SponserPackageID').select2({
        placeholder: 'Select a package'
    });

    $('#PrimarySponser_SponserInsurerID').on('select2:select', function (e) {
        var data = e.params.data;
        loadPayerNetworks(data.id, "PrimarySponser");
    });
    $('#PrimarySponser_PayerNetworkID').on('select2:select', function (e) {
        var data = e.params.data;
        loadPayerPackages(data.id, "PrimarySponser");[enter image description here][2]
    });
    
    function loadPayerNetworks(id,type) {
        $('#'+ type +'_PayerNetworkID').select2('data', null);
        $('#' + type + '_SponserPackageID').select2('data', null);
        $('#' + type + '_PayerNetworkID').select2({
            ajax: {
                url: '/Search/PayerNetworksByPayerId?id=' + id,
                processResults: function (data) {
                    // Tranforms the top-level key of the response object from 'items' to 'results'
                    return {
                        results: data.items
                    };
                }
            }
        });
    }

document.getElementById('PrimarySponser_SponserInsurerID').value="9"
document.getElementsByClassName("btn btn-success waves-effect waves-light")[0].click();