The grammatical person stays the same when you move from active to passive.
PassiveActivePerson
لَنْ يُفْعَلَلَنْ يَفْعُلَmasculine Ghaa'ib singular
لَنْ تُفْعَلِيْلَنْ تَفْعُلِيْfeminine Haadhir singular
لَنْ أُفْعَلَلَنْ أَفْعُلَMutakallim singular
First identify the Seegah, then identify whether the verb is active or passive.