Please try the the instructions below and let me know
1. From any Home screen, double tap the Apps icon.
2. Double tap Settings.
3. Scroll to 'SYSTEM' and double tap Accessibility (Touch the screen with two fingers and slide up or down)
4. Double tap TalkBack.
5. Move TalkBack slider to the left to turn off.
6. Double tap Ok to confirm TalkBack is turned off.
Comment the results below