To prevent floors from being moved, select “Lock Floors” from the Edit menu. This feature prevents floor shapes from being moved or manipulated. To unlock floor shapes, select “Lock Floors” again.
Since structural elements like floors generally precede interior elements like icons, this feature helps to avoid unintentional changes to floor shapes by allowing you to lock them down while you select, position and fine tune icons in your plan. A check mark in front of the menu command indicates that it is has been activated.
Note: You can lock an individual floor by selecting the floor. Then click on the "lock" button in the floor info panel.