How can my in-laws own my house?

My husband and I purchased our house 3 years ago. We used his parents as co-signers. However, they are the ones who own the house. We pay the mortgage and the insurance not them. Right now we would love to refinance, but because we don't own the house we can't do it. My in-laws have never had the income to purchase the house to begin with so they can't refinance it either. Could some one please tell me what went wrong and is there anything I can do to get it fixed...besides having them sell me the house.