How to go back to mac bootcamp. Just bought today my 21″5 iMAC and the installation of Windows7 with BootCamp was smooth and great, but i simple just can’t get to choose the option of which system i want to start when i boot the mac. OPTION KEY SIMPLE DOESN’T WORK, it always start with Windows7.Copy os x for macbook air 10. Copy, cut and paste are necessary functions for any computer user. Jul 3..