An error with Email Alerts setting!

Hi there, I have experienced an error occurring with a thank you letter which is sent automatically once the applicant submits their personal profile on system. I have double checked everything in setting so that the email alerts (a thank you letter), or all the template emails will be sent from Admin recruiter's email address @ yen.vu.thi@nextop.asia. However, something goes wrong causing above letter is now sending from a user in our system @ nga.quach.thi.thu@posismo.com. Could you please help to figure out this? Thanks!