If the Move tool is selected, holding the Command (Mac) / Control (Win) key temporarily activates the Auto Select (Layer) feature. To use Auto Select, simply click in the image area over the desired layer to select it in the Layers panel. Note: if you prefer, you can check Auto Select (available in the Options bar when the Move tool is selected) to eliminate the need for the modifier key. You can also Shift click on additional layers to select them. To select a layer using the context sensitive menus, Control (Mac) / Right Mouse (Win) -click in the image area over the desired layer and select it from list.