By default all components, including forms, have their VisualStyle property set to *NULL. If you are using one style consistently in all your applications, you may want to make that style the default for all the new forms you create.
To do this, edit the standard form definition, STD_FORM. Locate it in the Fields/Components list and open its definition. In the Properties sheet, specify the name of the visual style you want to use. Save the definition. From now on all new forms you create will use this visual style as the default.