This one http://prntscr.com/q7gr04 comes from theme styles and can be changed by adding the next code in style.css of child-theme or in Theme Options > Custom CSS area:
.tabs .tab-content p {
color: #222;
}
About your fixed header http://prntscr.com/q7gs43 , go to Theme Options > Header settings and change Fixed header color scheme.
Do not forget to clear the cache before checking he result.
