I filed an amendment and it was accepted. Can I change my banking info since the old one was closed before this was done?

[xmasbaby0]

The iRS does not permit you to change banking information after you file your tax return.   If your deposit goes to a wrong or closed account, it will be sent back to the IRS and then the IRS will issue a paper check and mail that check to the address you put on your tax return.  Make sure the address on your tax return form is your correct mailing address.

Do not expect quick results from amending. It can take four months or more for the IRS to process an amended return.  

You can watch for information here:

https://www.irs.gov/Filing/Individuals/Amended-Returns-(Form-1040-X)/Wheres-My-Amended-Return-1