The Sticky Menu (Or Anything) On Scroll plugin for WordPress allows you to make any element on your pages “sticky” as soon as it hits the top of the page when you scroll down. Although this is commonly used to keep menus at the top of your page, the plugin allows you to make ANY element sticky (such as a Call To Action box, a logo, etc.)
A little bit of basic HTML/CSS knowledge is required. You just need to know how to pick the right selector for the element you want to make sticky, and you need to be sure it’s a unique selector. Sometimes a simple selector like “nav”, “#main-menu”, “.menu-main-menu-1” is enough. Other times you will have to be more detailed and use a more specific selector such as “header > ul:first-child” or “nav.top .menu-header ul.main”.