you can change the a/c until you file the 2020 return. the earliest it can be filed will likely be late January 2021 when the IRS opens for e-filing. as of now its likely the IRS will use the same a/c as it did for the original EIP. if that's closed the deposit will go back to the IRS so a paper check can be issued. it will go to the last address the IRS has. if it changed you need to file form 8822 with the IRS and change of address with the USPS
https://www.irs.gov/pub/irs-pdf/f8822.pdf
