WordPress 3.3.1 not cropping featured image

By default, the_post_thumbnail() $size parameter is ‘post-thumbnail’. You can set that by adding this line to your functions.php :

set_post_thumbnail_size(125,125,true);

If this still doesn’t update your image’s size, you may need to use a plugin like “Regenerate Thumbnails.”

Alternately, you can set the image to use one of the Media Options-defined sized by passing a $size parameter to your thumbnail template tag like this:

the_post_thumbnail( 'thumbnail' ); // display post thumbnail with the "Thumbnail" size defined in Settings > Media.