Go to template settings -> Fonts section:
http://d.pr/i/sH2EThe setting in quick start are:
http://fonts.googleapis.com/css?family= ... 00,700,600Expletus Sans
body,
footer,
.gkMenu > ul > li,
.gkMenu > ul div.childcontent small,
.panel h3,
dl#tabs,
dl.tabs,
#loginForm h3,
#loginForm h4,
article li time
http://fonts.googleapis.com/css?family= ... ,latin-extNorican
#gkLogo.text,
.gkHeader h1,
h1,h2,h3,h4,h5,
.calendarCurrentMonth,
.calendarNavMonthPrev,
.calendarNavMonthNext,
.product_price,
.componentheading,
#member-registration legend,
.profile-edit legend,
.cart_subtotal_price,
p.numblocks span,
#gkCart,
.k2store_login_box legend,
.k2store_register_box legend
http://fonts.googleapis.com/css?family=Rock+SaltRock Salt
.box .header,
.box_menu .header,
.box_text .header,
#gkBreadcrumb,
#gkBg > footer,
li:before,
.pagination,
article time,
.itemAuthorDetails,
.itemAuthorDetails h3,
.k2CommentItem span,
.gkblock-9,
.gkblock-3,
.bubble-1 cite,
.bubble-2 cite,
.bubble-3 cite,
.gkTitle,
.gkChalkboard