In this case, you can downgrade because the very last MacBook Airs still first came with Yosemite. This one shipped with El Cap, but only because it was newly purchased and comes with the newest OS preinstalled; it can still run Yosemite if you want. (I do, so I understand completely. “macOS” had better be good!)
Standard procedure: go to App Store, grab Yosemite from your account, create bootable installer thumb drive, boot from thumb drive, spifflicate partitions on internal SSD. I would then shut down, perform SMC and NVRAM resets, and boot once again from USB. Now perform installation. For specific help please just ask. -- The following information is important for all members of the Mac Visionaries list. If you have any questions or concerns about the running of this list, or if you feel that a member's post is inappropriate, please contact the owners or moderators directly rather than posting on the list itself. Your Mac Visionaries list moderator is Mark Taylor and your owner is Cara Quinn - you can reach Cara at caraqu...@caraquinn.com The archives for this list can be searched at: http://www.mail-archive.com/macvisionaries@googlegroups.com/ --- You received this message because you are subscribed to the Google Groups "MacVisionaries" group. To unsubscribe from this group and stop receiving emails from it, send an email to macvisionaries+unsubscr...@googlegroups.com. To post to this group, send email to macvisionaries@googlegroups.com. Visit this group at https://groups.google.com/group/macvisionaries. For more options, visit https://groups.google.com/d/optout.
