Yes certainly possible. Pls insert the following CSS into Custom CSS tab in the Theme Options panel or the
/* To change the font for the navigation menu */
#primary-menu > ul.menu > li > a { font-family: Arial /* or whatever */ }
/* To change the font of the menu items you see in the dropdown */
.dropdown-menu-wrap ul.sub-menu li a { font-family: Arial /* or whatever */ }
Pls follow the instructions for import of the fonts as provided by your font source like Google fonts site. Hope this helps.