In Photoshop CS versions, Quick Mask Mode is accessed by pressing Q. But, in Elements, things are a little different
If you’re using Photoshop Elements, you may not be aware of Quick Mask mode. This is because it’s not as obvious as it is in Photoshop CS versions.
After making a selection and applying a layer mask, press the \ button to enter and exit Elements’s Quick Mask Mode.
The masked area will appear as a red overlay, onto which you can paint with the Brush or Eraser tools to edit the area selectively.