Hi,
open this PHP file:
/components/com_virtuemart/themes/flexible_vm_theme/theme.php
and find these lines below (line 164th) and read the instruction to increase the number of thumbnails:
/** START */
function vmlistAdditionalImagesBrowse2( $product_id, $images, $title='', $limit=1 ) {
/** $limit=1 represent; shown additional pictures will be maximum 3. if you want 4 thumbnails to be shown make it $limits=2. If you want 5, change $limit:3 AND SO ON. I hope you got the idea. If you set $limit=N, maximum N+2 will be shown in frontend. */
global $sess;
Regards,
Support