If you are new to Vegas it’s probably worth pointing out the four (4) places that you can add FX:
Master Video Bus FX: This is the FX button on top of the preview window. Any FX added here will affect the entire project. This is a good place to add FX like Broadcast Colors to ensure that your entire projet is broadcast safe.
Track FX: This is the FX button on the track header. Any FX added here will affect the entire track. Any video that you place on the track will have these FX applied.
Event FX: This is the FX button on right side of every event. Any FX added here will affect just the event. If you split an event with FX applied, each new event will have the FX also.
Media FX: This is accessed by right-clicking media in the Project Media window or by right-clicking an event and selecting Media FX. Any FX added here will affect ANY event that uses the media. This is great for color correcting cameras because the FX will be applied at the media level, so that when you use it in an event, the FX will already be there.
Only the last option (Media FX) will have the behavior you described (i.e., adding Levels to the media will affect all events that use the media). Hope this helps.
~jr
http://www.johnrofrano.com
http://www.vasst.com