@feruze-- Make your own yogurt! That's the only way to be one hundred percent sure that it's halal.
I've been making my own halal yogurt for years. I buy the yogurt enzyme online and I ferment my own yogurt which is so easy. And once you make halal yogurt once, you can use that to ferment the next batch. So you can make halal yogurt indefinitely that way.
I don't trust any of the ready-made yogurts, even if they claim to be halal. Plus, those have so many additives and preservatives in them that they are not healthy anymore.