If you change something in a system other than temperature, say concentration or pressure, the ratios of the reactants and products will be the same, so the value of Keq (based on the ratios of forward and reverse reactions) will not change. However, changing the temperature will shift the equilibrium towards either the endothermic or exothermic side of the reaction. For instance, assuming a forward exothermic reaction, changing the temperature to increase enthalpy (dH) will shift the system to the left which will produce more reactants than products, decreasing the Keq, which is based on ratios as mentioned before.