Mich. Comp. Laws § 490.58

Sec. 8. The presumptions stated herein are based upon inferences of the intention of parties to multiple-party accounts arising from the form of the account and the usual expectations of people using these accounts. The presumptions are rebuttable by clear and convincing evidence of a different intention. The presumptions of survivorship are not subject to change by will but may be rebutted by a written order received by the credit union to change the form of account or directing that payment not be made in accordance with the account which is signed by a party and is received by the credit union during the party's lifetime.