You can customize the preview settings for your Layer thumbnails by selecting Panel Options from the Layers panel fly-out. These settings can make it far easier to see the contents of a layer – especially when viewing on screens that have limited screen area.
• Select a desired Thumbnail Size. Note: if your image is significantly wider than it is high, selecting the smaller thumbnail sizes might display the generic icon for Adjustment layers.
• Under Change Thumbnail Contents, select “Layer Bounds” to display a preview image of only the area in the layer that contains content.
Select “Entire Document” to display the layer content in relationship to the entire document.
• Use Default Masks on Fill Layers will automatically add layer masks to Fill layers.
• Expand New Effects displays the contents of layer styles when applied.
• Add “copy” to Copied Layers and Groups will add the word copy to the layer name when duplicating layers in the Layers panel.