Highcharts export dateformat

Using highcharts v6.1.4 I can export without problems but I can not find a way to format the date that I transfer to my cvs, xls and table, they appear in format with unixtime example numbers:

1538917920000;19,3
1538917980000;19,5
1538918040000;19,6
1538918100000;19,5
1538918160000;19,4
1538918220000;19,2
1538918280000;19,3

Is there a way to show a date in another format? I need it to be '%e-%b-%Y - %H:%M:%S' => dd-mm-yyyy h:m:s

probe with this without results:

exporting: {
            csv: {
                dateFormat: '%e-%b-%Y - %H:%M:%S'
            }
}

Thank you for your attention. CDN:

<script src="https://code.highcharts.com/stock/highstock.js"></script>
<script src="https://code.highcharts.com/stock/modules/exporting.js"></script>
<script src="https://code.highcharts.com/stock/modules/export-data.js"></script>
<script src="http://code.highcharts.com/modules/no-data-to-display.js"></script> -->




var chart = Highcharts.chart('grafico', {

    global: {
        useUTC: false
    },



     xAxis: {
        labels: {

           format: '{value:%H:%M}',
        },
        title: {
            text: ''
        }
    },

    yAxis: { min: 0,
        title: {
            text: ''
        }
     },

    series: [{

        name : nombre_item,
        color: '#5c4ac7',
        data: processed_json,
    }],