In order to drag-select multiple layers, select the Move tool, enable (check) the Auto Select option in the Options bar and choose Layer from the pull-down list. Click and drag over content on a layer(s) with the Move tool (in the image area) to select the layers. This method works well if you have multiple layers and a Background. Otherwise, because you have the Auto Select feature turned on, clicking in the image area will select the first layer that you click on and begin to move it instead of selecting additional layers. Note: because a Background is locked by default, it is impossible to drag-select and therefore skipped by the Auto Select Feature. If you have layers that you do not want to auto select, lock them.