If you'd like to change the password used to gain root access to your Douro, you may do so, though please be aware that forgetting your new password may require reimaging the tablet to reset it to factory settings.
Connect a USB keyboard to the top of the Douro's Aaeon tablet.
Then press Ctrl + Alt + T to obtain a terminal window on the machine. Run:
Followed by the current root password (it will appear blank when typing).
Once logged in as root, run:
It will prompt you to 'Enter new UNIX password'. Specify here the new password you wish, and confirm when asked.
The machine will now use your newly defined password upon subsequent logins.