What do you mean by "in the 720 frame" exactly? Did you use Easy Set-up? Do you mean it only shows in the 720 frame size? Are you getting render lines or what?
How do you know it's only at 720? That sounds like a weird question, but I have a reason for asking it.
Sounds like you set up a 720 Sequence. Delete it. Go to the FCP menu, Easy Setup, and chose a project setting to match what your capturing. Then make a new Sequence. You can verify your Sequence settings by opening it in the Timeline window then going to the Sequence menu, Sequence Settings.
Once you set up a Sequence, you can change it's settings. But, once you drop footage into it, you can't change the settings or it will distort your already placed footage. You'd have to remove all clips from the Sequence, then redo settings, then drop footage into it.
But the Easy Setup is, well, much "easier" to use...