Setup:

So I recently booted a "KaliLinux.iso " into my 64GB USB drive. After doing that, I restarted my PC, and a prompt came up. From the prompt I selected "Live USB Persistence" . (I had no problem there but I think this may be causing my problem)

Issue:

I went to the terminal and put "apt-get update && apt-get upgrade". After a couple of seconds, it asked me whether I wanted to update it or not. I put yes and it started doing some work. As it neared the end, I told me that I had run out of space. I'm pretty sure it wasn't updating on my USB, but rather somewhere else. How can I either...
A) fix this issue?
B) make it so that everything goes to my USB?