That is correct. It has to be cancelled before midnight of first segment’s departure city time zone. It is also a good idea to write down the person you spoke with as well as time and date. If you cancel online, print out a copy of your cancellation.

Your canceled ticket’s credit is good for one year from original issuance date. You can call UA refund department at 888/551-6881, punch in your ticket number starting with 016. It will give you the history of that e-ticket.