<font face="Verdana, Arial, Helvetica, sans-serif" size="2">Originally posted by aussiemate:
I'm still in the US (in NY). I'm not aware of any Qantas offices here that I could go to.</font>
Presumably your ticket is a One World Explorer fare (fare code xONEn, e.g. AONE5), in which case any Oneworld airline can reissue it (not just Qantas). You could go to an AA office, for example. The segment can be changed for a fee (USD 75) as long as you have not left North America using that RTW ticket. Once you leave a continent any unused segments are gone.