On JA Onepage template, our template developers do include the scripts to control the duration of scroll templatesja_onepagejsscript.js file at lines:
$('.arrow-down, .btn-tpl-1').on('click', function(){
if (window.location.href.replace(/([^#]*)(.*)/, '$1') != this.href.replace(/([^#]*)(.*)/, '$1')){
return true;
}
var target = this.hash ? this.hash : this.href.replace(/.*(?=#[^s]+$)/, '');
if(target.substr(0, 1) == '#'){
target = $(target);
$('html, body').stop(true).animate({
scrollTop: Math.max(0, target.offset().top - ($('#ja-header').height() || 0) + 1)}, {
duration: 800,
easing: 'easeInOutCubic',
complete: window.reflow
});
return false;
}
});
You can try to change the red texts with your selected classes.