How can I change my image cropping dimensions?
All the image sizes are defined in functions/image-default-sizes.php here you can easily alter your image sizes. You could even copy the whole function into a child theme and override accordingly.
For example to alter the portfolio entries you would edit the following code:
//portfolio entries if( $args == 'portfolio_entry_width' ) return '400'; if( $args == 'portfolio_entry_height' ) return '320'; if( $args == 'portfolio_entry_crop' ) return true;
It should be pretty self-explanatory how to modify this