Creo Expert Moldbase Extension > Options > Assembly Options > PREVIEW_VIS_MODE
  
PREVIEW_VIS_MODE
disabled: Do not modify display and style in preview mode for components.
shade: Set display to shade when preview a component.
wireframe: Set display to wireframe when preview a component.
hiddenvis: Set display to hiddenvis when preview a component.
hiddeninvis: Set display to hiddeninvis when preview a component.
shadewithedges: Set display to shadewithedges when preview a component.
shadewithreflect: Set display to shadewithreflect when preview a component.
Default: hiddenvis