This feature effects the Mobile View of the theme that means changes can only be seen in the Hamburger Menu.
Recently the feature “Responsive Menu Style” was added on all of our premium themes for the better responsiveness in the mobile devices. Once this feature is activated, the sub-menu items in primary menu are visible only when the Arrow Icon floating to the right of the parent menu item is clicked. Before the introduction of this feature, the sub-menu items were displayed just beneath its parent.
However, this new approach may not be pleasing to all that is why, there is an option in the customizer through which one can toggle between the new Responsive Menu Style and the traditional menu. If you goto: Appearance->Customize->Header->Responsive Menu Style you can see a checkbox labelled Switch to new responsive menu. Stating the obvious: when this checkbox is checked, the Responsive Menu Style feature is activated, so if you want to stick with the traditional menu display then you can leave it unchecked. This feature is generally beneficial if you have large number of sub-menu items or have deeply nested menu items.
Below is a gif depicting the Responsive Menu Style feature on one of our popular preminum theme Accelerate.
Responsive Menu Style
