Originally Posted by
IAH-OIL-TRASH
Go to "Cancelled Reservations". You should see your original ticket there. You'll change the flights of that ticket to use the value of it. You will also have to give United a change fee in "new money" (it's not deducted from what you've already paid) to use the value of the original ticket.
Thank you so much for instant response. Where do I see cancelled reservations?
I only see -main menu Reservations -> Change or View Reservations and under that I see my one reservation that is inactive and there is this option to "Use Future Flight Credit".