Sometimes the solver in the tree is not changed by modifying the physics models from explicit to implicit and vice versa. The user should have check the integration method in the coupled flow physics model.
Details
If the user computes their simulation with coupled implicit, sometimes he/she would like to change the physics models to explicit. The user found it is not so useful, however, for his/her simulation and wanted to restore the model. To achieve this, the user changed the physics models from explicit to implicit. The solver in the tree is still shows coupled explicit. Even if the user removes all physics models and rebuild the models with implicit, the solver is not changed.
If you want to see the proper solver in the tree, you should change the integration method in the coupled flow physics model. It is fixed on explicit when the user selected explicit physics model but it will be changeable after modifying the physics models.