Online filing Change of Address is much easier

How Do I Report My Change of Address?
If you are not a U.S. citizen, changing your address for legal purposes does not change your address on any application or petition pending with USCIS and changing your address on a pending application or petition does not meet the legal requirements of informing USCIS of your change of address. You will need to do both. For most cases, you can now do both at the same time on our website using the Electronic Change of Address tool (available under "Related Links" on this page).

With the exception noted above, all non-U.S. citizens who move within the United States and its territories must a Form AR-11 within 10 days after completing the change of address. You can do that here on our website with the Electronic Change of Address tool. If you choose to use this online tool, you can complete an electronic Form AR-11 and notify USCIS to update your address on most pending cases.

http://www.uscis.gov/portal/site/uscis/menuitem.5af9bb95919f35e66f614176543f6d1a/?vgnextoid=9d686c854523d010VgnVCM10000048f3d6a1RCRD&vgnextchannel=54519c7755cb9010VgnVCM10000045f3d6a1RCRD