WinForm: How to use value of one Form in another Form

Question

#?Probem?
Supoose i have two Forms (Settings.cs and MainForm.cs) and a back-end class for methods(let, Compose.cs).

And, i want my Settings.cs to assign a DestinationFolder path(string) to Compose.cs file( public string destination{get;set;}) . So, that i can access that path in my MainForm.cs form.

But, when i access that 'destination' property it returns NULL. Though, i assigned my Folder Destination.

Image1: Setting.cs Form and Image2: MainForm.cs