Naming a beneficiary on a retirement account overrides whatever a will says, so a stale form can send money to the wrong person.
People spend money on a will believing it settles who gets what, then never look at the beneficiary forms attached to their largest accounts. That is a costly blind spot. For a 401(k), an IRA, or a life insurance policy, the name on the beneficiary form controls where the money goes, and it does so…