You may not really need a personal representative form, as you are aware, the other bank accounts passed to you by operation of law.
MCL 700.3982 provides:
(1) Upon a showing of evidence, satisfactory to the court, of payment of the expenses for the decedent's funeral and burial and if the balance of a decedent's gross estate consists of property of the value of $15,000.00 or less, the court may order that the property be turned over to the surviving spouse or, if there is not a spouse, to the decedent's heirs.
(2) Upon a showing of evidence, satisfactory to the court, that the decedent's funeral or burial expenses are unpaid or were paid by a person other than the estate, and if the balance of the gross estate after payment of the expenses would consist of property of the value of $15,000.00 or less, the court shall order that the property be first used to pay the unpaid funeral and burial expenses, or to reimburse the person that paid those expenses, and may order that the balance be turned over to the surviving spouse or, if there is not a spouse, to the decedent's heirs.
Thus if the balance of your husband's account was below $15,000.00 you may petition the Probate Court for an order granting the remaining account to you, if so a certified copy of that order should be sufficient for the bank.
If not you will have to file a petition with the court to open a probate estate for your husband, then petition to have yourself appointed Personal Representative. You can than present your letters of authority to the bank. That however can be a very cumbersome process.