How do I set Preview as default software for opening pdfs?

This response by Demo in Pittsburgh, PA answered my question.

Demo Pittsburgh, PA

Select any pdf file that you have on your hard drive. Get info on the file. Highlight the file icon and press the command and "I" keys to bring up the info window on that file. There is a bar that says "Open With" that allows you to select different applications to open that type of file. Select "Preview" from that list and then click "Change All" below that bar, close the info window and I think that will get you back to Preview for opening the pdf files.