When I speak, people may or may not listen. In order to move physical objects, I cannot command them to act. People are so excited today about voice commands on electronics where they can tell their phone, car, television or other objects to do something and they do it because of their programming. They have a different result however if they tell a storm to be still. Why is it different with God?
When I speak, I am creating sound waves that travel through air and cause other things to vibrate like my wife's eardrums. She hears and interprets the sounds as words and we interact that way. Is that what happened when God spoke to create the world? Did God send a message from one place to another within the universe?
I think the answer lies in the word authority. The base of that word is the word author. Why does the world change when God speaks? Because he is the author. He is not a character in the story giving dialogue, but because He is the author, His words write the story. Not the story in a book or drama, but the story of reality... his creation. In the beginning, God created the setting of the story.... His-Story. He spoke things into existence because He created existence. I have heard people question God's ability to affect their lives in certain ways and I have to laugh. God IS life. He created the very fabric of that which we question. How does God know and see and understand everything? Because, it came from His consciousness and His words.
The understanding of this is too complex for a mere character in the story like me to understand, but I know that I have the ability to interact with other characters, take action myself, and free will to do so given by the author himself. If I come across a situation, however, where I don't know where the story goes from here, or a situation where it seems the plot has become hopelessly tangled or stopped, I would be foolish to try to rewrite the story myself. Better to speak to the author, acknowledge His authority, and humble myself to receive the next page.
In order to do this, we must know the author personally. How do characters get to know the author? First of all because we recognize that we are in His story. The proof is around us in every aspect of our lives. Second of all, he gave us a little bit of help by send his so-powerful words to us to use for our own understanding of his authorship. The book is called the Bible. It tells about God, history, and even gives us a hint at the end of the story and the future words that He will speak to bring it all to a great conclusion in an eternal joining of the characters with the Author himself. Have a meet and greet with the author every day in prayer. Read the Bible to know the true story. What an amazing story it is.