Does flight compensation cover flights with changeover flights

pamela9234

we recently flew from Manchester u.k. to Buffalo, New York with a plane change at Washington. When we got to Washington our next flight was delayed twice then cancelled, we could not get on another flight that day with them but were offered a flight from a nearby airport on another airline which we took. The total delay time was 5 hrs. When I came to check in online for our return journey the website stated our booking had been cancelled. When I phoned the airline, they did not give me a reason or apology for the cancellation but offered me a flight from Buffalo to Newark, we had booked Buffalo to Washington, there was no alternative. The airline was American....I can only assume the airport clerk cancelled our return journey when he arranged the second flight from Washington. Can I claim for flight delay compensation on the first journey, my ticket was Manchester to Buffalo.....Can I claim anything for their cancelling my return journey? I did not want to fly TO Newark I was looking forward to flying to Washington then Manchester U.K.