I have a sequence in Final Cut Express 4 that has 1080p video in it, but when I export it, it exports as 720p video, because the sequence settings are set to 720p video. How do I change the frame size?
I think Menu -> Sequence -> Settings -> Load Sequence Preset..., then picking choosing a 1080p preset might do what you want. You'll probably have to delete and re-render anything you've pre-rendered.
You can set the default sequence preset for all new sequences with Easy Setup under the application menu.