Haw. Rev. Stat. § 560:6-105: Effect of written notice to financial institution.

The provisions of section 560:6-104 as to rights of survivorship are determined by the form of the account at the death of a party. This form may be altered by written order given by all parties to the financial institution to change the form of the account or to stop or vary payment under the terms of the account. The order or request must be signed by all parties, received by the financial institution during the parties' lifetime, and not countermanded by other written order of the parties during their lifetime.