A systematic study of the crystal structure and magnetic properties evolution upon chromium substitution for iron atoms in the (_{3-x}_x4) system is reported. According to neutron diffraction, Fe and Cr atoms are distributed unequally across the metal layers: with increasing (x), substitution occurs predominantly in completely filled layers, and at (x > 2), substitution also proceeds in layers with vacancies. At low temperatures, the saturation magnetization exhibits a minimum near (x ), which directly coincides with a maximum in the coercive field. Within a narrow concentration range ((0.75 < x < 1.25)), the ({3-x}_x_4) compounds display a giant exchange bias (EB) effect that increases exponentially with decreasing temperature below 50 K. The observed EB effect is attributed to the clustering of Cr atoms, forming quasi-two-dimensional regions that induce unidirectional anisotropy at the boundaries with coexisting ferrimagnetic regions. At 2 K, the exchange bias field during switching of ferrimagnetic clusters in the compound with (x = 0.9) reaches a value of 15 kOe. These findings demonstrate that engineering the atomic-scale cation distribution is an effective strategy for controlling macroscopic exchange bias in bulk layered chalcogenides.