Couldn't find the answer in search, my next LONE4 segment is scheduled for Mar 1 SIN-PER on QF I need to change this to an open date sometime in Apr.

Can I do this online or is it necessary to go to an airport?

The RTW was booked through AA but I assume since QF is the carrier I should contact them. The rest of the flights are open this is the last one with a date.