Hi,
In functions.php the specific dimensions for various locations within the theme are outlined. When you upload your image, based on those settings, multiple versions of the image are automatically created, each with the dimensions you specify in functions.php. Please take a look below:
$avia_config['imgSize']['widget'] = array('width'=>48, 'height'=>48 ); // small preview pics eg sidebar news, fullscreen slideshow thumbnails
$avia_config['imgSize']['related'] = array('width'=>130, 'height'=>130); // small images for related items
$avia_config['imgSize']['masonry'] = array('width'=>240, 'height'=>9999, 'crop'=>false); // masonry images
$avia_config['imgSize']['portfolio'] = array('width'=>200, 'height'=>140); // medium preview pic portfolio
$avia_config['imgSize']['blog'] = array('width'=>430, 'height'=>9999, 'crop'=>false); // image for blog posts
$avia_config['imgSize']['fullsize'] = array('width'=>1500, 'height'=>1500, 'crop'=>false); // big images for fuöösize slider
The fourth word of each line shows the location and later come the dimensions of the image. Whenever you see 9999, means that the image is going to keep its aspect ratio. The fourth word - Widget, Related images, masonry, individual portfolio, blog and full size are the various images. You said you wanted blog changed? Right now width is set at 430px while height is 9999. also crop is set to false, so it will always be proportional. So, you can either :
a) change height from 9999 to whatever you want and set crop to true.
b) Go to the backend > settings > media and change the Maximum Width and Maximum Height of the Medium Image (if you want to maintain the aspect ratio of the image.
Since I can't see your site I hope I understood your requirements,.
Thanks,
Nick