The Play vs Computer in v3 only supports Standard and 960 at this point.
Can i change modes against the computer?
Does anyone know which engine is used for the computer opponents and the analysis?
Nothing official, but months ago I was over at V3 when the code was still a little rough around the edges and managed to drill down to a Stockfish screen. Could have been just something they were trying out though, and no, I can't find it again. Let's mark that down as a question to ask Erik next time he does a "State of chess.com show". It would be nice to know, although they're not about to give out any secrets about how it's set up.
STOP POSTING NOW. I NOW KNOW HOW TO CHANGE IT.