Lenovo A2107A - Manual (Page 24)

Screen lock: You can unlock the display in one of four ways: Slide,
Pattern, PIN and Password. You can deactivate the screen lock as well
by selecting None as well.
Tap Pattern, and use your finger on the screen (as illustrated) to
draw an unlock pattern. Once you have set the unlock pattern, you
will then be able to toggle Make pattern visible on/off.
After you have set and activated the pattern unlock function, the
unlock keypad will be displayed whenever the display is to be
unlocked. Use your finger to trace your preset pattern on the
keypad. After the preset pattern has been correctly entered, the
screen will be unlocked.
Tap PIN to input the PIN code (minimum 4 digits) you will use to
unlock the display.
Tap Password to input the password (minimum 4 characters) you
will use to unlock the display.