There are 2 ways to lock the Extension:
Option 1: Directly click lock icon on the right corner of the home screen
Step 1: Click home icon on the left corner of the home screen
Step 2: Select Lock Extension
Step 3: Choose Confirm to lock your extension
Step 1: Open Extension and click unlock
2a: If your password is text password, enter your Text password and click Unlock
2b: If your old password is matrix password, move your mouse until the number gets into the right position.