PINE64

I'm by no means a master at Linux so this application is fantastic for me.  

I'm trying to figure out how to use the 128gig thumbdrive as a system storage drive to load and save files to. I'd like to make it the download path for Firefox. Just not sure how to mount and direct the OS to it. Any info would be greatly appreciated. This will defiantly help me to learn Linux a little easier. Thanks again!

whats the usb drives format ?  The drive should show up in your file manager (not sure what Q4OS uses - Doplhin?) when you plug it in. If it doesn't, open terminal and type: sudo fdisk -l  
Paste what it prints out here. 

As for firefox, once you get your drive set up, you can just go to preferences in firefox -> general -> save files to 
and select the mounted drive or a folder within.