Featured Image Size smaller after updating

in new version, there’s an option to use what featured image size.
check theme option->posts setting->featured image size
use medium for previous set, default is thumbnail now.

Thank you for your answer!now is well

Hello Richie,
still in the phone does not look like before

https://dl.dropboxusercontent.com/u/234469602/Ana%20DIY%20Crafts/mobile%20.jpg

what i can do to make it look like before?

thank you

add this to theme option->custom css
@media only screen and (min-width:200px)and (max-width:500px){
#custom #post-entry div.post-thumb {width: 100%;}
#custom #post-entry div.post-thumb img {width: 100%;height:auto;}
#custom #post-entry article .post-right {margin:5px 0 !important;float:left;width:100%;}
}

Thank you Richie! that’s work fine ??