Have you taken a look at devtools in your browser?
You’ll find out all sorts of information there. (including that this is a messy theme!)
I’m not sure what the CSS is that you put in your post, it doesn’t seem to have anything to do with your menu.
First of all, the actual menu is
ul#avia-menu.menu.av-main-nav. The menu items that you listed [test, exam, hello, apple] are actually siblings of the search button as well. Those are all set to
float: left, while the search button is set to
float: right. That’s the first part of your problem… if you follow so far, you should be able to dig in and fix it up.
If not… for this theme, did it come with this menu, or is this menu a widget? Are there options inside the WP admin to modify it?