Hamburger stays put when scrolling

Hi. I am employing the Hamburger Icon Menu Lite plugin to generate a hamburger menu. It operates, but when I scroll the webpage, then hamburger stays at the top rated of the exhibit, and is not anchored to the best of the webpage.

What is causing this to materialize, and how can I notify the hamburger to keep at the top of the page when scrolling? I am missing one thing. Many thanks!

Below is what the plugin generates: