So i been using this theme for my blog which has so many customization options that you can get lost easily. I am doing one step at a time so i thought i should change the menu style but after spending some time i found the place. Probably you can do that as well but i thought this post might save you some minutes.
If you have your menu under the banner then go under ‘Other graphical elements’ and click ‘ Navigation bar below header’ in that there are the following options
Menu Item Style – Show menu items as individual tabs
Menu item style – Show menu items as a continuous list
