Menu problems since update

I am using the Evolve theme on a clients site for a while now and I just upgraded the theme to the newest version. Now I have menu problems. The submenu-items do nog show when I hover over the main menu item and furthermore when I click on a menu item I don’t go the page I want but instead there expands my whole menu down the screen. Then I have to click on the item I want to go to the page. How do I get rid of the drop down and go back to it just going straight to the page desired? And also how do I see my sub items when hovering over the menu? I am trying for a while now with coding and all kinds of things but no result. Also deactivating plugins one by one without result. Site is on maintenance mode so if you need a link let me know. Please help.