What Language file to change for BO Orders Table "Payment"

[Rhapsody]

When I upgraded from 1.5.3.1 to 1.5.4.0 there were some subtle language changes. The Orders table in the BO has a field called Payment that displays the payment method (e.g. PayPal, Check, etc.). I had it previously so when someone paid by Check displayed "Check", but now it displays "Payment by check".

 

What translation do I need to change using the the BO localization menu so the data to populate this table displays what I want it to?

 

I have copied the default theme to another name and customized it, so assume I would be changing that custom theme.

Edited March 29, 2013 by Rhapsody (see edit history)