[Theme Horse Support Team]

Hi whoisjackie,

Blog image large is our default layout. So blog image medium will only displayed on choosing blog image medium template. On tag, category etc it will display blog image large. To have blog image medium it needs code customization. Go to theme folder -> library -> structure -> content-extension.php on line no 131 you will find this code

$image .= get_the_post_thumbnail( $post->ID, 'featured', array( 'title' => esc_attr( $title_attribute ), 'alt' => esc_attr( $title_attribute ) ) ).'</a>';

replace with

$image .= get_the_post_thumbnail( $post->ID, 'featured-medium', array( 'title' => esc_attr( $title_attribute ), 'alt' => esc_attr( $title_attribute ) ) ).'</a>';

Note: We recommended not to change the code because if you change the code then while updating to our new version all your customisation code will be lost. So better make child theme and first unhook the functions and the edit the code.

http://codex.wordpress.org/Child_Themes

Thank you!