What's the logical fallacy for when you change your mind on something and then people label you as wrong?

Not sure, but I’m sure you’ll find your answer here
http://www.nizkor.org/features/fallacies/

Wishy Washy

It might be considered a kind of Ad Hominem argument/attack. Y isn’t addressing the arguments X has for changing his mind about global warming, or Y’s arguments for now supporting global warming, but is arguing against X’s changing his mind itself, a personal attack independent of the arguments for or against global warming. But I don’t think there is a logical fallacy specifically addressing a person changing his mind about something.

If one changes his mind, he must offer victory to his opponent. At that point, the debate is over, and Mr. X has lost. I think at that point Mr. Y is free to say anything he likes. ^_^

I look at all things I have answers about like this. “X=Y with the information I have thus far. Perhaps new information would reveal that Y=Z. Therefore, X=Z. And, a whole new door opens. That’s life. Basic math.

Maybe Ad Hominem Tu Quoque?

In politics, the attack label is Flip-flopper. Claiming your policy proposal is wrong because you previously proposed the opposite, but changed your mind is an ad hominem attack on you that avoids addressing the policy proposal. Suppose someone once supported the death penalty for all parking violations, but upon learning more about the gravity of such crimes and how redeemable many of the guilty parties are, they changed their mind. Would that mean they are now wrong, and that we really should impose the death penalty for all parking violations? I certainly hope not.

@liminal
Yes.

@ETpro
Yes…the death penalty for all parking violations. But, only if you are a politician. ~

@MissA Stone all miscreants of all kinds, I say! Oh wait… I changed my mind about that. Amnesty for all.

Not a fallacy, AFAIK, just standard antagonism.