If you want to merge all layers in Photoshop, there are a few different ways to do it. The easiest way is to use the Layer Menu (Window > Layer Menu). From here, you can select Merge Layers. If you want to merge all layers automatically, you can use the Automation Tool (Window > Automation). From here, you can select Merge Layers from the Automation Options menu. Finally, if you just want to merge a specific layer without merging any other layers, you can use the Layer Masking Tool (Window > Layer Masking) and select Merge With Selection from the Mask Options menu. ..