Hi linkrep42,
You should be able to change the sizes by editing the functions.php. Here's the instructions.
Open functions.php and locate the following lines.
$avia_config['imgSize']['widget'] = array('width'=>36, 'height'=>36 ); // small preview pics eg sidebar news
$avia_config['imgSize']['slider_thumb'] = array('width'=>70, 'height'=>50 , 'copy'=>'greyscale'); // slideshow preview pics
$avia_config['imgSize']['fullsize'] = array('width'=>930, 'height'=>930, 'crop'=>false); // big images for lightbox and portfolio single entries
$avia_config['imgSize']['featured'] = array('width'=>990, 'height'=>360 ); // images for fullsize pages and fullsize slider
$avia_config['imgSize']['portfolio'] = array('width'=>448, 'height'=>334, 'copy'=>'greyscale'); // images for portfolio entries (2,3 column)
$avia_config['imgSize']['portfolio_small'] = array('width'=>241, 'height'=>179, 'copy'=>'greyscale'); // images for portfolio 4 columns
//dynamic columns
$avia_config['imgSize']['dynamic_1'] = array('width'=>488, 'height'=>160); // images for 2/4 (aka 1/2) dynamic portfolio columns when using 3 columns
$avia_config['imgSize']['dynamic_2'] = array('width'=>671, 'height'=>231); // images for 2/3 dynamic portfolio columns
$avia_config['imgSize']['dynamic_3'] = array('width'=>761, 'height'=>160); // images for 3/4 dynamic portfolio columns
Edit the size for this line:
$avia_config['imgSize']['portfolio_small'] = array('width'=>241, 'height'=>179, 'copy'=>'greyscale'); // images for portfolio 4 columns
Once done save/upload your functions.php then go to Media and regenerate all your thumbnails. You'll also need to edit your CSS accordingly.
Hope this helps!
Mya