I wanted to notify that I have been assigned as the new person in charge.
I wanted to notify that another person has been assigned as the new person in charge.
ご質問ありがとうございます。
まず、主語による英文は違います。下記の2つ英文を作りました。
もし、自分で新しい担当者になったをお知らせしたい場合、「I wanted to notify that I have been assigned as the new person in charge.」という風に言えます。
もし、あなたは現在の担当者ですが、これから別の担当者に変わる場合、「I wanted to notify that another person has been assigned as the new person in charge.」と言えます。
ぜひ、適切な英文を選んでください。