Use this IRS website for stimulus payment status or to update your bank account - https://www.irs.gov/coronavirus/get-my-payment

Use this IRS website for get my payment FAQ's - https://www.irs.gov/coronavirus/get-my-payment-frequently-asked-questions

You can try making the change on the IRS portal: Get My Payment | Internal Revenue Service

If you are unable to change it, your payment will be declined by the bank and the IRS will send you a paper check to the address on your tax return.