Hi,
Sorry for the late reply. Usually when the settings in the design panel are not applied you have created a custom view for the article add-on. When using a custom view it does not take the settings in the design panel into account, you have to do all the formatting (html/css) yourself.
To reset the custom view, go to the article add-on and edit the custom view. Delete all code in it and save the view. Once done the settings from the design panel will be applied again.