one line navigation

This is likely a CSS styling issue. Breadcrumb NavXT does not supply any CSS for the frontend. So you’ll need to add some CSS to your theme or child theme’s style.css.

There are several ways of fixing this. Typically, you can set the containing element (likely a div or nav element with class breadcrumbs) to float either left or right. I suggest using an in browser inspector such as Firebug in Firefox, or the developer tools in Chrome to interactively play with the needed CSS until you achieve the desired result.