Here's how you can easily change your video preferences in iTunes from 720P to the higher resolution 1080P.
1. Open iTunes.
2. Click on iTunes in the menu bar.
3. Click on Preferences.
4. Click the Playback tab.
5. Click the drop down menu next to Preferred Video Version and select 1080P.
6. Click the OK button to save your changes.
1080P video looks significantly better than 720P, so it's well worth your time to make this change. Please note that you will need to redownload any videos currently in iTunes to take advantage of the higher resolution in iTunes. You can do that by going to your Purchased list in the iTunes store.
Read more: iLounge