When clicking Edit button from the main Account screen there is no possibility to edit account billing information.
Finanical information can now be edit by using Edit link (under Financial Information and Billing Contact Information), this information will be included into the documentation (documentation bug with id #PBA-63590 ).
There is a request #PBA-63349 for the screen redesign, as the button name are not clear, there are duplicate Edit links and when editing financial information the buttons are located in the middle of the screen.
Note: User needs ACCOUNT_MODIFY_TERMS privilege to see Edit button (under Financial Information and Billing Contact Information). Resellers do not have this privilege by default.