it might not be the reason or only reason you did not get the jo

If I were you, I would have said: I liked the bank and worked very well with everyone, however, i realized that the bank officer job was not for me. I prefer doing xxxx (the job you are interview for). This job (the job you are interview for) seems to be challenging and will allow me to improve and grow.
 

Just my 2 cents. Good luck!