As noted in one of the FAQs, CMW does not provide any styling at all. There is nothing in the CMW options that specifically/knowingly provides for outputting a menu that displays horizontally: it’s purely down to your theme. With no other influences, the output will display vertically because that’s the nature of a list (UL/OL).
You can change the styling of any menu using your theme, possibly in conjunction with a specific id and/or classes set on the CMW menu in question. Exactly how you do that depends on all sorts of things (which is why CMW leaves it you!), such as :
- your theme may already have CSS set up for a horizontal menu, whereby you simply need to add a class into the relevant CMW option
- your theme may have an option that permits entry of custom CSS via admin, or you may have to modify a stylesheet (preferably in a child theme)
- you may just want the level 1 items to be horizontal, with sub-menus menus vertical, or you may want all levels to be horizontal (or you may only have 1 level)
- you may want javascript interaction to show sub-menus … or not
- you may want any number of tweaks to spacing, colours, alignment, fonts, responsiveness, etc
One way to get things “horizontal” is to float them (usually left). Another way is to set them to display inline, or inline-block. Whichever you use, you probably need some sort of qualifier (id or class) to target just that menu and its elements.
If you were to provide an accessible example, and maybe expand a bit on your requirements (rather than just “horizontal”), then I might be able to be a bit a more specific with the CSS you could use?