Except as otherwise provided in section 554.9340, subsection 3, and unless the bank otherwise agrees in a signed record, a bank’s rights and duties with respect to a deposit account maintained with the bank are not terminated, suspended, or modified by:
1. the creation, attachment, or perfection of a security interest in the deposit account;
2. the bank’s knowledge of the security interest; or
3. the bank’s receipt of instructions from the secured party.