Locking and Unlocking Objects
You can lock objects to avoid inadvertently moving them as you work.
After you lock individual or grouped objects, you can’t move, delete, or modify them
in any way until you unlock them. However, a locked object can be selected, copied, or
duplicated; when you copy or duplicate a locked object, the new object is also locked.
To lock an object:
Select the objects you want to lock, and then choose Arrange > Lock.
To unlock an object:
Select the objects you want to unlock, and then choose Arrange > Unlock.