If you are tying to change a setting or add a feature to a post and can’t locate the option to do so, that option may not be enabled in Screen Options. Click on the Screen Options tab at the top right corner of your WordPress screen to view all the options that are available for the function you are currently performing. Different options are displayed depending on whether you are editing a page or post, adding media, etc.
Screen Options available when editing a page or post:
Screen Options available for the Dashboard: