Select All Layers in Photoshop
Selecting multiple layers at once makes organizing and transforming your document much faster. Here’s how to select all layers or build a custom multi-layer selection with simple keyboard modifiers.

Step-by-step instructions
1
Select all layers at once
Open the Layers panel.
Click the bottom-most layer to select it.
Shift-click the top-most layer to select everything in between.
2
Select specific layers non-contiguously
Ctrl/Command-click individual layers to add or remove them from the selection.
Repeat to build the exact set of layers you need.