I have NEVER been successful in changing flights on co.com and I do it a fair amount. I always end up having to call the elite line. I had the issue today - I needed to change outbound and return; however after putting in the new date for both - it only changed my outbound and kept my return 6 days earlier so another call to the elite line; the agent I had was very helpful and quickly made my return change. I've had Y or A fares and it changes it to lowest available; therefore putting me in the back. So another call. I am unsure why this glitch has not been fixed; but I have yet to make it work online. Good luck and try the new 75 sunscreen