Accessibility questions

Hello!

An accessibility checker keeps pointing out a few things, such as "Ensure links are distinguished from surrounding text in a way that does not rely on color". But the only links that it lists and that are not underlined on my page are those inside the navigation drop-down menu at the top of the page. Am I supposed to have the menu selections become underlined when a user moves over those choices? If so, how do I accomplish that in Website Builder? Also, in the advanced settings, I have "AJAX-based navigation" checked. What does that do as opposed to non-AJAX-based navigation?

Also, could someone please explain "Ensures all page content is contained by landmarks" and "Landmarks should have a unique role or role/label/title (i.e. accessible name) combination". It looks like my page is already subdivided into sections and I've already gone through the sections of the page and made sure that every section has a Combo Box setting of either "Header", "Footer", "Nav", "Article", or "H1", "H2", etc. Are there some settings, such as "Aside" or "Article" that I should avoid? Could there only be one "Nav" section on the website that contains the pull-down menu? Can there be several sections "H1" or "H2". There doesn't appear to be a way to add a distinct id attribute or aria-label to each section under Website Builder, but they seem to have different names, such as "Section A", "Section 1", etc. What do I need to do to either add distinct ids or aria labels?

Thanks!

Alex.