I had a flight from PHX to BOS (connecting via DEN) at 2pm. W class ticket. I am Premier Gold.

My last day meetings got canceled. I called United the evening before departure at 9pm asking to change to an earlier flight departing at 8am which had lots of seats on same fare class. Agent said need to pay change fees and the earlier 24 hour (flat tyre rule) is gone. Is this true?

I went to airport at 6am hoping to get standby on 8am flight. Check in agent said standby rules allow only for same connection city and 8am flight was via ORD. I argued my origin & destination are same, but no luck.

Has there been a big change in the rules? Any advice for future travels?