I don't think I've ever discussed my former therapy with a new therapist. I always just went in starting fresh. I don't even recall a therapist ever asking me any specifics about former therapy; they also seemed to want to get to know me from their own perspective.

Perhaps go in with a discussion of exactly what you would like to work on in therapy with this therapist. Now, if your past therapy experience is one of those issues, then I'm not sure how you can avoid talking to the new therapist about it, but perhaps you could reframe the issue. Are the problems you ran into with your therapist in some way similar to other relationship issues you've had in your life? Is there a common thread there that you want to address? That might be a truly productive way to start establishing some goals to work on with this new therapist.