You must change ownership using something like:
sudo chown ahmed:ahmed /home/ahmed/.config/codeblocks/default.conf
This is because you executed C::B as root, do not do this.
Miguel, The other C::B files are still owned by root which could cause issues down the track. Better to run the following (and potentially against ~ just in case for non Linux users)
sudo chown ahmed:ahmed -R /home/ahmed/.config/codeblocks