Hope you are having a nice day.
Mobile menu starts from 992px. If you want to change this breakpoint it requires a lot of additional style customization. But you may add this code in Theme Options > Styling > Custom css > Custom CSS for mobile landscape (481px – 767px):
Sorry, but unfortunately, this request falls to the customization and out of the general support responsibility, in this case, you can contact these guys for the customize service: WP-Kraken team.
Hope you understand this matter, thank you.