You can lock elements to avoid inadvertently moving them as you work.
After you lock individual or grouped elements, you can't move, delete, or modify them in any way until you unlock them. However, a locked element can be selected, copied, or duplicated; when you copy or duplicate a locked element, the new element is unlocked.
Select the elements on the page you want to lock, and choose Arrange->Lock.
Select the elements you want to unlock, and then choose Arrange->Unlock.