With its multiple layers, the advanced layout is naturally more flexible than the simple layout. It is also true for the masking workflows. You can create different masks for the different layers (or if you want, copy the same mask to all of them).
Let’s start with a very simple case: you want to keep the details of a portrait, as we already saw it with the simple layout. Flexibility has a price, you have to execute a few steps that the simple layout provides out of the box.
1. Add a new original image layer below the effect layer (the + button is in the Layer Browser toolbar)
2. Add a mask with the Mask button (it is also in the Layer Browser toolbar)
3. Click the newly appeared mask thumbnail in the layer (it will display the mask properties, replacing the style properties in the editor)
4. Adjust the mask strength
5. Set the position, size, aspect ratio and rotation
6. Blur the mask and adjust the strength if necessary
When you want to edit the style properties again, just click the style thumbnail in the layer.
Other mask options are accessible from the layer context menu (right click).