In the early church all things were owned in common. By what authority was this changed?

By the authority of the failure to obey. Just ran out of willing participants.

Acts chapter 2 is about the day of Pentecost. (You gave the wrong reference, should be 2:44-45.) Back up and read verses 1-5 and it will become clear that what is being talked about is events that took place in Jerusalem. Verse 46 tells us that they continued daily in the Temple.

Many had came to Jerusalem for Pentecost and I believe what you are seeing here is that they pooled their resources in order to remain in Jerusalem (where the Temple was). I do not believe that this was a picture of christianity as a whole but just this particular congregation.

whatever verses is that it doesn't matter but that's what the bible stated, whoever changed it? well most probably the members itself 'coz no one follows it anymore for men instinct is to have for their own interest and to save for themselves. Just like today if the concept would not materialize change it to another w/c would do. And all religions practice this kind of changing to meet the desire of men instead of God.

All that means is that that particular group found it worthwhile to live in that way. What makes you think that it was a recommendation that people live like that forever? Where does it say "this is how people should live two thousand years into the future?"

By the authority of Evolution from Socialism into the Capitalism system of ownership. I like the Capitalistic way better. Socialism promotes free-loading, and I am of the opinion that, "He who does not work should not eat."

no commune lasts... someone always gets power hungry...

It smacks of COMMUNISM!

HORROR! SHOCK! PANIC!