Editing the Responsive menu

I would like to edit the mobile and tablet portions of the menu to be a drop down on all mobile devices. When I look at it on apple devices a scrolling menu appears. I have gone into the css and found were the code for mobile menus live. I cannot seem to find the part that edits this particular function.Would this be a javascript thing?

This is not css/js/html type of menu - this menu uses standard select html element and depending on device it renders differently.