Hi Nino,
Can you explain more on what you mean by BaseApplication?
If you are consuming an Entity of a different module, and that Entity is marked as Expose Read Only, you can only use the Get action of that Entity. Same thing applies for Static Entities, as well.
To be able to change data of an Entity in a different module (where that Entity is being referenced), you need to create public CRUD database actions (Create, Update, Delete etc.) in the module where the Entity is situated, and use them in your target module.