The Clone Stamps Tool works by sampling pixels from a source layer and applying them to them to targeted layer( the target layer can be the same layer or different layer) To make a source. in addition, sample click Alt and click on the area you want to replace and also, It's a powerful tool that, rather the area like other retouching tools, copies and replaces pixels. Before you start any retouching, create a new layer Layer>New and select Sample All layers in the toolbar. By cloning to a new layer, you protect the original image pixels so you can reverse any change you make.