Matanus,
Are you talking about the config button from the main menu left from the about button? No issues here.
Could you try it again making sure you hit the button with a firm press. An maybe a reboot in advance.

It could also be caused by the gngeo config file not being as aspected. For that you can start by:

python /opt/gngeo-gui/gngeo-gui.py

from the xterminal and see what the output is when you choose config.