With Photoshop Elements 2018 and 2019 the Healing Brush Tool doesn't react to the usual shortcut in order to change the brush's size. This can only be achieved using the mouse.
Everything is in German: Windows 10, Photoshop Elements and the Keyboard Settings. What makes me wondering is that the Spot Healing Brush Tool is working with the above mentioned shortcuts ('shift #' and '#'). The same applies to the other tools whose size can be changed, like the Selection Brush, Eraser or Brush.