If everything is "greyed out", UC Surface on your your new computer has no permission to control the mixer. Go to "System" on your mixer, page 3, look for the device (your computer) and activate the settings "FOH" and "Ch.Rename". This should get you going.
StudioLive AI Software Reference Manual, chapter 3.5 (http://www.presonus.com/support/downloads)
Hope this helps.