Hi,
Do you want to apply one skin to the whole application, that means to all forms and controls?
If yes then remove all LookAndFeel components and ensure that the LookAndFeel.UseDefaultLookAndFeel property of all forms and controls is set to true.
Also put the following code into the Main method of your application to apply e.g. the "Black" skin to the whole application:
static void Main()
{
DevExpress.Skins.SkinManager.EnableFormSkins();
DevExpress.LookAndFeel.UserLookAndFeel.Default.SetSkinStyle("Black");
Application.EnableVisualStyles();
Application.SetCompatibleTextRenderingDefault(false);
Application.Run(new Form1());
}