Internet Speed

I am paying for Preferred Internet which is stated as up to 50Mbps. When I ran the internet speed test on Cox, I only have 9Mbps download and 4Mbps upload speed. How can I get the internet speed higher?

Before I moved my service to a new address, I had the same package and had about 48Mbps for downloading. The internet also seems to drop connection intermittently in my new address. The house we are living in now is in a new development. Does that affect speed and connectivity?