There are two possibilities. 1) God made the world in 6 days, but put lots of stuff in it to make it look very much older.
2) God made the world in 4 billion years featuring a neat invention we call "Evolution", but some peoples interpretation of the Bible is wrong.
Since no two denominations can agree on the meaning of the important parts of the Bible, I prefer to think that #2 is the correct answer. I just don't think God plays practical jokes like making the world old just to mess with us.
making the world old = making the world appear old
What if he was in a hurry?