A file which is edited on a USB drive will not be updated on the hard drive which a copy of it is also on. This is obvious, but to make this idea clearer, imagine if you copied a file from your hard drive onto a USB drive. Now take that USB drive and plug it into a different computer. If you update the file on that USB drive, will the same file on your other hard drive somehow know of this change and update itself? The only way which this synchronization could take place, is if both your USB drive and hard drive were connected to the same cloud storage... which isn't too likely.
