@Fazal_E_Rabbi, your case is a bit different. It’s not the same bug as the OP.
In 3.1.15, Composer 2 and Composer 2 Fast were merged into one item in the picker, and Fast is enabled by default. To switch to regular Composer 2, hover over the model in the list and click the small Edit button on the side. You’ll see a Fast toggle there. Turn it off.
The Edit button is really not obvious. We’ve already collected feedback about it in nearby threads: Composer 2 fast is the only option in UI , Composer 2 normal is not showing, Where did Composer 2 non-fast go?.
Let me know if you can’t find the toggle.