how do I go back from El Capitan to Mountain Lion
Made a BIG mistake by loading El Capitan...how do I go back to Mountain Lion?
iMac (21.5-inch Mid 2010), OS X El Capitan (10.11), want to get this os off my computer
Restore from your Time Machine backup. However before you go to those lengths, please post anEtreCheck report of your system and we can look for obvious issues.