sub-menu not in vertical

this is the theme : AgentVersion: 1.2.31
By Prothemeus

And this is the site http://star.webexperts.pt/

The thing is that i am trying to edit the sub-menu but it’s always a issue with the body when the sub-menu appears, and i can’t put in horizontal instead of it’s normal state.

this is how i would like to see it
https://www.dropbox.com/sh/9f1etsw35lwjroo/AAAZrL6HJZqGNxFkTC_UC1L4a?dl=0

it’s this to complex and i leave this idea behind or it’s easy and i can use for example a plugin to set the sub-menus