I just got a new iMac desktop and I don't have a mouse yet only a keyboard to login with at startup. Does anyone know what keystrokes to use to select the box that pops up requiring you to sign in to your iCloud? I had it working the other night and then I updated the system which kicked song that I was using for a mouse off and I am unable to use that now just trying to login so I can use the computer help somebody please thank you in advance