If your last filed return has a bad address on it then you need to mail in a form 8822 :
https://www.irs.gov/pub/irs-pdf/f8822.pdf
The missing first 2 stimulus payments should have been reported on the 2020 return you filed as a credit on line 30 of the form 1040. The third stimulus payment would be released once they process the 2020 return ... if you don't get it by January then that will be a credit on the 2021 return.
