Contribution Amount Label Not Translated through Word Replacements

Starting with 4.2, the label for contribution amounts on online contribution pages is stored in the DB as a price_field.label for the hidden 'quick config' price set. This means Word Replacement will not affect this label. In order to change it the user needs to switch to using a 'regular' price set for the online contribution page and then edit the price field label.

For 4.4 we'll expose the price field label on the Amounts tab to make it a bit easier if user just wants to change the label:
http://issues.civicrm.org/jira/browse/CRM-12055

— original post —
I am unable to change the text that reads "Contribution Amount" to "Payment Amount" in a contribution page. The contribution page has "contribution amounts" section enabled, but with no price-sets set. Allow other amounts is enabled and there are no Fixed Payment/Contribution Options defined.

Also, when no amount is entered into the "Contribution Amount" field, the error reads "Contribution Amount is a required field." Word Replacement failed to change this to "Payment Amount is a required field" as I would like it to read.