Hi,
here the steps:
1. copy focus.php from /components/com_community/templates/jomsocial/layouts/profile/ to /templates/[your site frontend template]/html/com_community/layouts/profile/. create this location if not exist yet (/html/com_community/layouts/profile/)
2. edit that file (new location file), at line 103, find this code
<img src="<?php echo $user->getThumbAvatar() . '?_=' . time(); ?>" alt="<?php echo $this->escape( $user->getDisplayName() ); ?>">
with this code, the avatar size only 64 x 64. please changing it to
<img src="<?php echo $user->getAvatar() . '?_=' . time(); ?>" alt="<?php echo $this->escape( $user->getDisplayName() ); ?>">
with this code, the avatar size will be 160 x 160
and for changing the size, please put this CSS code at your site template custom CSS. every joomla site template must be can put custom CSS code. please find it at site template documentation.
.joms-avatar--focus img {
max-width: 160px;
}
please do not edit jomsocial css (Style.css) it will disappear at upgrade process, because that file as part of jomsocial core files.
Regards