As far as I'm aware, v3 isn't the default yet so you would have to actually click a link to switch.
That said, the resign button looks like a flag 
Some of the changes are talked about in the following.
https://www.chess.com/article/view/introducing-chess-com-version-3
V3 sucks. It looks awful and is harder to use. This is how they spent my money.
V3 sucks. It looks awful and is harder to use. This is how they spent my money.
Well, v3 was well in progress when you joined.
The membership is to access the site tools (videos for diamond, mentor, additional tactics), no advertisements and for many auto-vacation. Updating the site to be more manageable, on the back-end, and at the same time modernizing the front-end is just a bonus 
I've been here since 2011. V3 is horrible. Scrap the whole idea and move on to v4,which I hope is more like v2.
Thanks for the warning!
I was into a game with no idea where the controls were. Couldn't resize the board, couldn't find the resign button (embarrassingly) - couldn't easily see the taken pieces.
Seriously, and info message with a bit of a guide would have been nice. Does one exist?
Where is the resign button anyway? It's only visible (usually) during a game, so not the best time to be hunting for it.