I understand that the model explorer of your Simulink model is completely grayed out, due to which you cannot change the value of any parameter. Based on the available information about the model, the parameter is disabled for one of these reasons:
- The parameter has a dependency on another parameter. In this case, the parameter becomes enabled or disabled depending on the setting of the other parameter. To enable a parameter that has a dependency, see the complete documentation for that parameter.
- The configuration is a configuration reference. In this case, all of the parameters are disabled in the dialog box. To change the parameter values in the referenced configuration, see - https://www.mathworks.com/help/simulink/ug/referencing-configuration-sets.html#bq2wh78-7
For further information, refer to the documentation links below: