Highcharts - Where is the location of 'back to {series.name}' in Yii2?

Does anyone know where the back to {series.name} button's location? I want to edit it to be back to previous

I'm using this:

use miloschuman\highcharts\HighchartsAsset;
    use yii\helpers\Url;
    use yii\helpers\Html;
    use yii\bootstrap\Dropdown;
    HighchartsAsset::register($this)->withScripts(['modules/exporting', 'modules/drilldown']);  
    $this->title = 'Highcharts Test';