Thank you for reporting this PHP 7 "Too few arguments" error.

It has been fixed for UBB.threads 7.7.2



in admin/edit_subscription.php
FIND:
Code
$admin->setParentTitle($ubbt_lang['SUB_SETUP']);

REPLACE WITH:
Code
$admin->setParentTitle($ubbt_lang['SUB_SETUP'], null);

current developer of UBB.threads php forum software
current release: UBB.threads 8.0.1 // wip: UBB.threads 8.1.0
isaac @ id242.com // my forum @ CelicaHobby.com