Increasing the size of avatars

I want to increase the size of the avatars displayed with the comments. I’m using version 2.7 with the iNove theme. My blog is at https://3widealley.com/wordpressblog/?p=155

I’ve searched the style sheets, comment sheets and others, but can’t find anything… any help pointing me in the right direction would be appreciated.

I did try adding this code to the themes comments.php file:

wp_list_comments (‘type=comment&callback=custom_comments&avatar_size=64’)

This had no effect on the comment page.