This sounds like heading tags... https://www.w3schools.com/tags/tag_hn.asp
That's how visitors using screen readers, and even search engine robots, skim your page for important content. Visitors with screen readers tab through headlines and hyperlinks.
I don't know what your buttons look like. But if you split up the content on 14 pages, then your content isn't easily accessible. The scene has to load and then the visitor has to go back to return to the list. Also, I don't see how you setup your buttons. If you have 1, 2, 3, 4, 5... etc... without any descriptive words... then that's not accessible either.
Maybe create the links to the scenes manually. Just use regular HTML, with descriptive words and hyperlinks.
1 - Introduction
2 - Beginning topic
3 - More about the topic
4 - Advanced discussion about the topic
Older help document, but it seems manually created hyperlinks can be used to load scenes...
Also, you could use a persistent symbol so that the visitor doesn't lose the navigation. You might need to use a tab index to help people get around. That might help too.
Without seeing the project, it's hard to see what's wrong. Although, I rarely download forum attachments here – security reasons. Other people are less squeamish though, especially the guys that make the software. So, posting an actual project might help them help you.