top menu not working from 'single page'

well that's a little of a shortcut, don't you think?
actually see the text on your the templates demo-site:

"Making Normal Single Pages

You can use this template to make normal single-article pages. Do this as you usually do with any other Joomla template. You need to make an article page and to create a menu item (type: single article) that's assigned to the article. The result can be seen in this sample single page."
demo.hotjoomlatemplates.com/index.php?template=one_page

Ok, I understand what you ask. You problem is that menu items search for anchors located on home page that do not exist on you single page.

You can create one more menu with same items but in that new one you will set link class to value of 'external' (type in external) for each menu item that points to anchor on home page and you will add home url in front of anchor link.

You will create menu module for other menu and use menu assignment to control which shows where.

So for example

menu item on home page link is

that link on menu on single page will be:

thx,

gonna work on it.
have nice weekend.