Hi - I am selling a 2012 MBP and have just erased the hard drive and restored it to factory settings. I was using El Capitan before I wiped it, but when I restored it to the factory settings, I think it re-installed Mountain Lion. The person buying it tried it out when El Capitan was installed. Am I right in thinking that they can upgrade to El Capitan when they set up the MBP with their own Apple ID? Thanks.