I'm sorry I don't know about Vietnam. What I heard is they are more strict in terms of bank statement. The one I met in Cambodia was rejected in Laos but approved in Cambodia.
I'm sorry I am not sure I understand your question.
Do you mean bank certificate?
I think it may vary individually. I cannot tell for sure but the one I met in Cambodia who is also a Burmese got her visa approved without submitting bank certificate.