Can't get off Root on hard drive to change owner

It worked on the other computer and the other hard drives.
This is a storage hard drive. I backed up my data - formatted it to ext4 and gave it the name it had before. The mount point is /media/rjsmith/RJS
then ran > $USER:$USER /media/rjsmith/RJS
came back > command not found.

Now I did try to expand the partition on it with Gparted but that failed. I don't think that has anything to do with it. But it is what I tried after changing it to ext4.