Events have a set of default values such as an Event Image (not used by all M/IC Apps), Feed URLs and other settings that the developers of the app has specified. These settings apply to just a single Event, not to the whole project.
Every Event has its own Event-level settings. Note that if you change one Event you may need to change others. You can edit the Event settings within the Timeline view by clicking Edit Event, or from the Schedule tab within the Event's drop-down.
Event Settings can be changed and saved within the Event Settings tab:
Note that Event Settings can differ between apps.