You have to enter analysis mode first. It will bring up a screen like this, and the little icon for computer is what you need: Oh well, the copy and paste didn't survive the journey back from V3. I'd go back and try again but this already cost me 3 points off my TT score. 
Tactics Trainer - try vs computer
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Dec 1, 2015
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#3
Sorry about the 3 point loss. i did figure out what you meant without the picture. However, that didn't quite work. When I follow your directions, the tactical trainer scenario comes up but it picks up one move in ahead of the TT scenario....and the computer does not make the move that it makes in the TT scenario. I've tried twice now with the same result. Is there some way to pick up the scenario at the point where it's my move in the TT scenario?
live2beoutside wrote:
Sorry about the 3 point loss. i did figure out what you meant without the picture. However, that didn't quite work. When I follow your directions, the tactical trainer scenario comes up but it picks up one move in ahead of the TT scenario....and the computer does not make the move that it makes in the TT scenario. I've tried twice now with the same result. Is there some way to pick up the scenario at the point where it's my move in the TT scenario?
Why don't you press that little bug reporting icon (the one that looks like a bug) and let whoever is working on the TT know your concerns? Sorry I couldn't help much.
I've searched the forums and cannot find any information on this topic - when I study tactics trainer sessions, I cannot find the link on the new chess.com site that allows one to try the scenario against the computer. Given my current low ranking and lack of understanding for the game, I find that I need to actually see alternatives play out against the computer in order to fully understand why many of my tactical decisions are wrong. I have tried continuing to do tactics trainer sessions in the old version, then switching to the new version after clicking the "try vs computer" link - sometimes it works, but in most cases, the computer fails to make a move. I am unwilling to continue to use "try vs computer" on the old version of chess.com because of the issues with JAVA no longer being supported for Windows 10 and Google chrome.
Any ideas on why I can't do tactics trainer sessions vs the computer on the new chess.com? Is this feature still being developed? Will it be eliminated with the new site? Is it just my computer?