Thank you for your reply.
Unfortunately the client keeps insisting on this matter. I tried to install a menu extension, and enable it in the menu module area but it stays as shown in the page stj-gb.gw/

It opens vertically, not horizontally. Is the template also not built to work with a different menu, or can I change it?
Thanks once again

Please ask the menu developer please.
Because I dont know this menu extension

We are committed to help you with any type of support query, however we can't provide extensive help in terms of customizations. In general customizations may look simple but you will require solid knowledge of web technologies and programming skills to do them or hire a professional who can do it for you.