[Solved]-Stop HighCharts change transparency of another series on hover of one series-Highcharts

You need to change the opacity property for inactive state:

plotOptions: {
    series: {
        states: {
            inactive: {
                opacity: 1
            }
        }
    }
}

Live demo: http://jsfiddle.net/BlackLabel/7fmcp0da/

API Reference: https://api.highcharts.com/highcharts/plotOptions.series.states.inactive.opacity