As you work with your page layout, layers can be activated, selected, or resized. Putting layers in active mode lets you place content in layers. Selecting layers lets you align, reposition, or resize layers. Resizing layers lets you change the dimensions of a single layer or make two or more layers the same height and width.
Different Property inspectors appear when you work with single or multiple layers. See Layer properties and Setting properties for multiple layers. Also, the layer Modify menu options are enabled only when multiple layers are selected.
To prevent layers from overlapping each other, use the Prevent Overlap option. See Preventing layer overlaps.