There is a interesting gray period between a schedule change and the acceptance of the change, at that point the traveller has some room for negotiation with UA. Depending on the amount of change (especially if over 2 hours, as in this case), UA may be willing to look at alternative routings and waive change fees or even a full refund without penalty. It is best if you have have an alternative in mind.

However, if as channa mentions, your travel agent has accepted the change for you, a power you may have delegated, then the negotiation window is closed and your beef is with the TA.