When I use Avid DVD 5.2.1 and I send to DVD one step I get 4:3 DVD but I want 16:9. What to do?

Consult the Help->Avid DVD by Sonic Help menu.  When the online help manual opens look in the index under "aspect ratio->movies".

But this is just when you send it to DVD Authoring, not when you use send DVD one step!

that's an interesting issue.  the software is not recognizing your timeline as 16:9, so you have to manually override in the movie attributes window when the application is open.  Here's a rough workaround.  Send your timeline to Avid DVD by Sonic, create a movie with it in Avid DVDs timeline.  go in the movie attributes window and change the setting to 16:9.  Close Avid DVD.  go back to your timeline in Avid and try the one-step again.  More like a 3 step, but it should work as long as the same asset is being referred to in the one step as was imported into Avid DVD.  once you change the assets aspect ratio in Avid DVD, it should be changed for all future projects using that asset.

Unfortunately it´s not working. The 16:9 setting is not in the project preferences settings saved. So I get the 4:3 DVD again.

Try the track asset itself. Click on the track, and check it's property. It should have an option in the track property for 4:3 and 16:9. Select 16:9.

 

There is no possibility in the track asset. I can see the aspect ratio in the movie properties but I can´t change them in the timeline just the movie propertries for the whole dvd. Even when I set the Q-Ref to 16:9 it´s again 4:3
in the movie properties.

Were you ever able to get DVD One Step to work for 16x9 or did you have to use an external program?

No, I never get it to work. I could just use the send it to button to have 16:9. But mostly I use a normal DVD recorder today, so I don't have to render all effects.