Refer: https://askubuntu.com/questions/944852/how-can-i-change-the-username
First, make sure you have root login access, from a root shell prompt, enter the following then exit and re-login, and you'll be fine.
Create a temporary admin account to run the following, then after you logon to jboss1, rename the account and delete the temp account.
$ usermod -l **new_username** -m -d /home/**new_username** **current_username**
$ gedit /home/<username>/.config/gtk-3.0/bookmarks