Thanks, dreadpiratetrey!
The post and widget titles are displayed in bold because this is defined in the theme styles and is not adjustable via the Theme Options. You can, however, change this by adding some code to the “Style: Add Custom CSS” tab of the Theme Options panel:
.serif, cite, h1, h2, h3, h4, h5, h6, #content h1 a, #content h2 a, #content h3 a, #content h4 a, #header-image h1 a, #header-image h2 a, #header-image h3 a, #header-image h4 a, h1 a:visited, h2 a:visited, h3 a:visited, h4 a:visited {
font-weight: 400 !important;
}
Sincerely,
Andrii / Satori Studio