How do I change the name of my DVD

Must I "start over" to do that, or can I "fix" my iDVD project somehow?

You can just change the name of the project in Finder

The name already IS "ABC" but when it makes the DVD it names the DVD MY GREATDVD, not "ABC" like I want it to.

I am not sure what you mean by "title page" the name of the .dvdproj is "ABC.dvdproj"

When I have iDVD running, it shows "ABC" at the top. When it makes a DVD it calls it "MY GREATDVD".

I am using iMovie 06 with iDVD 08/09.

The main title is "ABC". I thought that was just text anyway. But it is also called "ABC". But when I burn the DVD the name of the DVD is MYGREATDVD.

I found it! Project > Project Info > Disc Name.

That is the area that contains the name of the disc. I think normally that area is pre filled in using the filename.

Because my filename was more than 26 characters long iDVD may have changed it to MY GREAT DVD. There may have been a warning to this effect but I missed it.

I go so fast with iMovie 06 and iDVD 09 (the same as iDVD 08) that I may have missed this.

Thank you for helping someone in the "colonies". I have marked your post as solved.