Thank you, Darrel.
I have been able to get it working, however when I first open the Lectora file it says that it is missing two resources: Resource 7250 and Resource 7251.
Also, I find that I have to amend the html file every time I publish (to html). (I must admin I only just manage to fumble my way through the code as I am not an expert.) Is there a way to change the settings (e.g. number of parallax scrolling objects, the speed and location, etc) inside Lectora itself, without having to manually amend the html code?