Or in your site front page, in the admin bar find Edit Page ( Back-end Editor ) or Edit with WPBakery Page Builder ( Front-end Editor )
For changing size and margin, go to Theme Options > Header > Fixed Side > Logo element
Instead Quick Contact also you can create any page and assign it.
For changing the Shape of Arrow you can go to Shape tab of this element edit box.
For editing menu navigation settings go to Theme Options > Header > Fixed Side > Menu Element
And for styling menus go to Theme Options > Header > Fixed Side > Menu Styles of this Row
you can set the hover FX and styling the icons via options and Stylekits there
For changing margin (Position), go to Theme Options > Header > Fixed Side > Social