Originally Posted by
carrotjuice
I thought EU261 compensation is calculated based on the entire trip (how long it takes you to reach your final destination) so CPH-SIN-BKK, not just the SIN-BKK connecting segment.
Correct, the flight was operating from EU country (Denmark) so definitely falls under EU261/4 and the full flight distance counts. Assuming I understand correctly and the OP arrived over 3 hrs late into BKK then he is owed 600 Euro per pax compensation under EU261/4 unless SQ can prove extraordinary circumstances.
Then on top of it comes a downgrade of the SIN-BKK sector which may not yield much in the sense of compensation on its own as others explained, but could be combined with above claim.
Op should definitely read up on his/ her rights under EU261/4 and check maybe with Danish (assuming they reside in Denmark) transportation authorities guidance for consumers/ passengers if new to the regulation.