Try to add the following code snippet to the Custom CSS area in Theme Settings and you need disable all fonts in Theme Settings / Typography.
@import url(http://fonts.googleapis.com/earlyaccess/notosanstc.css);
/* main navigation font */
.main-nav .menu > li > a {
font-family: 'Noto Sans TC', sans-serif;
}
/* Primary font */
h1 a, h2 a, h3 a, h4 a, h5 a, h6 a, h1, h2, h3, h4, h5, h6, .title, table th, .wc-tabs li a, .masonry-filter li a, .woocommerce .cart-empty, .basel-navigation .menu > li.menu-item-design-full-width .sub-menu > li > a, .basel-navigation .menu > li.menu-item-design-sized .sub-menu > li > a, fieldset legend, table th {
font-family: 'Noto Sans TC', sans-serif;
}
/* Entities names */
.product-title a, .post-slide .entry-title a, .category-grid-item .hover-mask h3, .basel-search-full-screen .basel-search-inner input[type="text"], .blog-post-loop .entry-title, .single-product-content .entry-title, .font-title {
font-family: 'Noto Sans TC', sans-serif;
}
/* Text font */
body, p, .widget_nav_mega_menu .menu > li > a, .mega-navigation .menu > li > a, .basel-navigation .menu > li.menu-item-design-full-width .sub-sub-menu li a, .basel-navigation .menu > li.menu-item-design-sized .sub-sub-menu li a, .basel-navigation .menu > li.menu-item-design-default .sub-menu li a, .font-default {
font-family: 'Noto Sans TC', sans-serif;
}
/* Widget titles font */
.widgettitle, .widget-title {
font-family: 'Noto Sans TC', sans-serif;
}
/* Secondary font */
.title-alt, .subtitle, .font-alt, .type-post .entry-meta {
font-family: 'Noto Sans TC', sans-serif;
}
.
