[@solhuebner Participant 13 years, 1 month ago]

Try adding

function subscribed_by_default() {
	echo '<script type="text/javascript">jQuery("#bbp_topic_subscription").prop("checked",false);</script>';
}

add_action('bbp_theme_after_topic_form_subscriptions', 'subscribed_by_default');
add_action('bbp_theme_after_reply_form_subscription', 'subscribed_by_default');

to your functions.php