How do I access the SD card in my Android 5.1.1 Samsung Galaxy S5?

[AC Question]

I am trying to replace my 2 Gig SD card with a 128 Gig version. I want to keep the data that is stored on the 2 Gig card, but can't seem to connect to my PC through the USB cable. USB debugging is turned on, but I still can't access the phone from the PC. Any ideas on what I'm missing?