I can see that you did the changes; as I warned, getting this to work for you might be quite the challenge!
So first, some background on what is causing the issue.
So there are several issues with your site that are completely out of the control HD Quiz. These issues are CSS related to your theme / other plugins.
The way that the auto-scroll works is that HD Quiz needs to figure out not just where on the page it should scroll to, but what is the element that should be scrolled. Because of the way your site is coded, it’s basically impossible to calculate this.
We are using the Enable Legacy Scroll
feature for your site which gives us more control over what, when, and where the scrolls appear. However, by default, this feature is not enabled because we allow the browser to figure this out itself. So the fact that even the browser itself is unable to accurately figure out where and what to scroll points towards there being some serious issue with your site layout and CSS. Unfortunately, debugging your site to track down these issues is far out of scope for HD Quiz support, but luckily we can still do some modifications to the plugin directly to compensate for this.
To make this easier for you, I have made the modifications myself to the hd-quiz/includes/js/hdq_script.js
so that you can just copy / paste the entire thing. I’m fairly certain this will work for you, but if it doesn’t, it should also console.log
some extra information that we can use to help us moving forward. Here is the modified code: https://pastebin.com/raw/mr1Bj7CU
Please let me know if the above makes any difference and I’ll take a further look.