Ok, this means that /home/dxhum is your home directory so Firefox should be downloading to /home/dxhum/Downloads/I found this line in the file:
dxhum:x:1000:1000xHum,,,:/home/dxhum:/bin/bash
Sorry, just an old DOS guy learning Linux.
(I cut and pasted the line from the file. Not sure why the smilie showed up)
Make sure to use:
$ cd
Use pwd to see if it says /home/dxhum first.
$ ls -al
Then see if your directory uses permission 0700 as it should. Then look at Downloads to make sure it uses 0700 as well. 0700 for a directory looks like drwx------.
Signed,
Matthew Campbell