the default labels of the DoubleList widget
webix.i18n.dbllist = {
selectAll: "<span class='webix_icon fa-angle-double-right'></span>",
selectOne: "<span class='webix_icon fa-angle-right'></span>",
deselectAll: "<span class='webix_icon fa-angle-double-left'></span>",
deselectOne: "<span class='webix_icon fa-angle-left'></span>",
};
webix.i18n.setLocale();
You need to call the setLocale method to apply the new format settings