Unable to move layers around in layer panel

Hi there,

I was able to drag and move my layers into folders and sort them on the layer panel, but now all of a sudden I cannot. I am using a new Mac laptop. I did some research and discovered that the command key with square brackets will move the layers, but still cannot just use the mousepad or drag a layer into a folder. I just upgraded everything this year, so I am only 6mos into using this version of Photoshop whereas the previous version I used for years was CS 5.5.  Any suggestions would be helpful. Thank you