I dont understand how the laws can change from one universe to the next

For me it'll change my concept of physics should it be true

However whether proven or not I fail to see how it debunks theist arguments, other than in fact strengthen them. If science can be rubbished like this, then the belief that their is a god (or Gods for each universe) fine tuning each universe becomes all the more plausible
If there were one universe and it was perfect, or multiple expansions all also perfect then the argument could be made "Who did the fine tuning?" However if you have an incomprehensibly large number of expansions with slightly varying tuning then it shows that we just happen to be in one of the well tuned ones whereas there are many others not well tuned.
It's like the old "Goldilocks zone" argument for Earth. If we didn't have another 7 planets in our solar system it would have more credibility, but when we observe our solar system we see many other planets not in this "magic zone" and then when we look at the universe on a much wider scale we see not only multiple planets in this magic zone but an even more massive number of planets that are not.
Or to put it another way. It's like throwing a box full of little praying dolls in the air and then pointing out the minority which face Mecca and saying "There, Muhammad MUST have been God's messenger!" - given enough random shit + the ability to selectively ignore data you can see a pattern for anything.