  The electrical polarization switching on stoichiometric GaFeO$_{3}$ single
crystal was measured, and a new model of atomic displacements responsible for
the polarization reverse was proposed. The widely adapted mechanism of
polarization switching in GaFeO$_{3}$ can be applied to stoichiometric,
perfectly ordered crystals. However, the grown single crystals, as well as thin
films of Ga-Fe-O, show pronounced atomic disorder. By piezoresponse force
microscopy, the electrical polarization switching on a crystal surface
perpendicular to the electrical polarization direction was demonstrated. Atomic
disorder in the crystal was measured by X-ray diffraction and M\"ossbauer
spectroscopy. These measurements were supported by ab initio calculations. By
analysis of atomic disorder and electronic structure calculations, the energies
of defects of cations in foreign cationic sites were estimated. The energies of
the polarization switch were estimated, confirming the proposed mechanism of
polarization switching in GaFeO$_{3}$ single crystals.
