IDVD widescreen preview problem. I want 4:3

Go into your Users/Home/Library/Preferendes folder and move these two files to the Desktop:

com.apple.iDVD.plist

com.apple.iDVD.LSSharedFileList.plist

Reboot, launch iDVD and try again. This time don't burn but follow this workflow to help assure the best qualty video DVD:

Once you have the project as you want it save it as a disk image via the File ➙ Save as Disk Image menu option. This will separate the encoding process from the burn process.

To check the encoding mount the disk image, launch DVD Player and play it. If it plays OK with DVD Player the encoding is good.

Then burn to disk with Disk Utility or Toast at the slowest speed available (2x-4x) to assure the best burn quality. Always use top quality media: Verbatim, Maxell or Taiyo Yuden DVD-R are the most recommended in these forums.

If that fails, go back into your Users/Home/Library/Caches folder and move the com.apple.iDVD folder to the desktop. It will be regenerated the next time you use iDVD. Reboot again and try iDVD once more.

NOTE: In Lion, Mountain Lion, Mavericks, Yosemite, El Capitan and Sierra the Home/Library folder is now invisible. To make it permanently visible enter the following in the Terminal application window: chflags nohidden ~/Library and press the Return key - 10.7: Un-hide the User Library folder.

Or for Mavericks, Yosemite, El Capitan and Sierra go to your Home folder and use the View ➙ Show View Options menu to bring up this window:

The latest version of iMovie only works with 16:9 widescreen, the format used in all modern cameras and TVs, monitors etc.

Which is why iDVD defaults to it. When you start a new project in iDVD you get the option of setting it to either Standard 4:3 or Widescreen 6:9