Thanks for asking.
As you are using Pro Theme I suggest you to header builder. As the navigation is divided into two parts displaying on left and right side of the screen. Please do following:
- Add a Bar and under Flex Layout > Horizontal and select Space Between.
- Add two containers and in each of the containers add Navigation Inline element.
- To have a sticky navigation, please inspect the Bar and unser Setup turn on Sticky Bar option.
To learn more about header builder, please take a look at following resource.