(1 & 2) The Holy Prophet Muhammad, may the peace and blessings of Allah be upon him, cursed the accepter of interest and its payer, and one who records it, and one who bears witness to it.
لعن رسول الله صلى الله عليه وسلم آكل الربوا وموكله وكاتبه وشاهديه .
Hence any such job of the bank in which one is directly involved in the interest transactions is not lawful as per the Shariah. The cashier and officer of a bank help in interest directly hence it is not lawful to work on the post of bank cashier or officer as per the Shariah. Therefore, you should look for any lawful job and when you get one you give up this job immediately and also keep on doing taubah and istighfar. Also supplicate Allah to provide you halal and pure job.
Allah knows Best!
Darul Uloom Deoband