Please try following steps to enable the passcode protection.
Tap “Settings” in the main menu.
Tap “PasscodeLock” and turn “Simple Passcode” switch off, if you don’t want to use the 4 digit simple passcode.
Tap “Turn Passcode On” and enter your passcode.
Swipe the screen up to see the bottom of the screen.
Turn off the “Starting” and other switches except for the wallet.
Now you are ready to use passcode protection for the wallet.