[Solved]-How to change axis label size when exporting in Highcharts / Highstock-Highcharts

put this inside your chart: {}

events: {
                    load: function(){

                        if (this.options.chart.forexport) {

                            highcharts.each(this.series, function (series) {
                                series.yaxis.update({
                                    labels: {
                                        style: {
                                            fontsize: 6
                                        }
                                    }
                                });
                            });
                        }
                    }
}