Kapi1904

A few months ago I cancelled my flight due to a schedule change. Unfortunately the change was too minor to get a full refund. UA allowed me to use the ticket value for future travel waiving the change fee.
Talking back then with UA agents I understood that I have to complete all travel for the new itinerary within 1 year of the original ticketing date. However I am not too sure anymore if this is really the case. I have found other rules that state that I have to do the change (reissue) within 1 year from the original ticketing date and then all travel has to be completed within 1 year from the date when the ticket was reissued. That means that in the best case I would have 2 years from the original date of ticketing to complete all travel. It is an international ticket from Germany to US. Could anybody give me advice or is there any official policy that applies to this case?