Why Beta value is changing and very low in this circuit
The transistor is in saturation, not the forward-active region. You can tell because \$V_{\text{CE}} \approx 84\text{mV}\$; when \$V_{\text{CE}} &lt; 0.2\text{V}\$ or so, the transistor is in saturation. \$\beta\$ is high in the forward-active region but is lower when in saturation.

To get the transistor in the forward-active region, you need to lower the voltage drop across \$R_1\$ (which has the effect of increasing \$V_{C}\$ and therefore \$V_{\text{CE}}\$ as well). You can do this either by lowering the resistance value of \$R_1\$ or reducing \$I_C\$ (set by \$I_E = V_E/R_4\$, which is in turn set by \$V_B\$).