How to Use Stamp Visible Layers in Photoshop
When you’re working with multiple layers you can use the Shift+Ctrl/Cmd+Alt+E keyboard shortcut to activate the Stamp Visible command.
This creates a merged version of all your layers at the top of the stack – just like the Layer>Merge Visible command would do.
However, Stamp Visible has a big advantage over Merge Visible. Merge Visible flattens all layers in the Layers palette, rather than placing them on to a new one.