Overriding a specific display doesn't work
It's easy to miss if you're always clicking on the | Settings link of an Option. 

Options can be set to apply to All displays or you can override for each Display separately This attachment (override). 

But you have to click on the Option itself and not its "Settings" link to see that Dropdown. 

You clicked on the "Teaser" or the "Featured" Settings link of your Show Option, but there is no Dropdown to override there. 

You have to click on the Content link first, Override through the Dropdown for this Attachment only and Apply (this display). Then you can change the Settings for the Option if you have to. It will only apply to the current Display. 

You can change the original Display Option to what you want and Apply to all displays, that one doesn't have to be overridden, unless it makes sense for that particular case.