How do I turn on / off TalkBack mode?

To turn on the Talkback mode: Go to Settings > Accessibility > TalkBack > Toggle on > Tap OK to turn on

To turn off the TalkBack mode: Go to Settings > Accessibility > TalkBack > Toggle off > Double tap to toggle off > Tap OK > Double tap OK to turn off. 

Note: You will need to touch and hold your selection for 1-2 seconds so it is highlighted by the green box. Once highlighted you will need to double tap to make the selection.