Services featured image zoomed in on page header, options revert to default ?

Hello Hopefully someone might be able to help me here. I have set some services, included a featured image which is a small icon. They look great on the home page but when you click the continue reading button the featured image is massively zoomed in and pixely in the header on the main post page. I figured that the featured image options at the bottom of the services page editor might fix the issue. But if i change the options they dont do anything and always revert back to 'default'. Any help would be very much appreciated.