Amended return

We filed our taxes for 2020 in February and had to pay into federal taxes. Since then the healthcare credit was changed and I am unable to get to a screen to file an amended return.

When I opened the software, it updated and showed we are due a refund of $186.00 from federal. Then I went to the amended form and  corrected the healthcare credit and it shows there is no refund due. Since we paid in over $800.00, our total refund should be over $900.00.

Please advise how to file an amended return.