If you are appointed executor of someone’s Will, then yes, you need the change the name on the accounts that is in the decedent’s name. The decedent is the individual who has passed away.
As executor, your job is to collect all the assets of the estate. When you become executor, you need to get a tax id number, and it is with that tax id number that you open an estate account. Then, all of the assets will be put into that state account.