What are you saying sound strange. I think you are wrong something or you think it works in a different way. Cinelerra-GG doesn't work like AdobePremiere; from some points of view it works like Lightworks, if you know that NLE.
Please take a look at http://www.visi1.org/cinelerra-gg_tutorials#DragAndDropEditing from 6:55 to 7:53 (08-4. IMPORTANT--> Note_1): the Group must be selected before. And the tracks (Video + Audio) armed.

(I am using the Cin_20201031 release on UbuntuStudio_16.04)

But back to my question, how to connect audio to video. The group is not very stable. When saving and reopening a project, the binding of the group is no longer effective.
Do you who use CIN GG with success not have a need for a stable connection of the video track with the associated audio track, as is the case with most video editors?
I mostly work with videos with the original sound. If I'm not totally careful, the tracks shift, and it's very unpleasant when the picture and the sound are no longer exactly in sync.
Question: If this feature doesn't exist in CIN GG, would it be a lot of effort to add that?

@Michi wrote:

How to avoid that the group is not only shown in one color, but that you can also see the video image of the track?

You can change the opacity using the slider on the bottom of the Main window, on the right side. Take a look at http://www.visi1.org/cinelerra-gg_tutorials#ColorTitleBarsAndAssets around 1:00. If you can see all the video is better, I think.

wonderful, have now watched your two videos. Forgive me for not doing so right away. Unfortunately my English is quite weak, but I find the videos very good. The accompaniment of the written texts is very helpful.
I understood a lot. So you can form a group. That is already very good.

How to avoid that the group is not only shown in one color, but that you can also see the video image of the track?

Have you seen my previous links to http://www.visi1.org/cinelerra-gg_tutorials#DragAndDropEditing and https://streamable.com/o4sgg7 to understand how Group works, please?

thanks for the info.
When I see your videos, I have the impression that you know a lot about CIN GG.
In the forum I have already asked how to chain video and audio track together, so that they always remain in sync, even if I move a track. I got some tips to avoid that. But I haven't discovered a method to link tracks firmly or to form a group, unfortunately. Is there really no such thing?

No, the design is not change. Cinelerra-GG has some themes. I use S.U.V. theme, you  are using Cakewalk theme. You can change it in MainWindow-> Settings-> Preferences-> Appearance tab, "Layout" section-> Themes.

Here a old video to show  that: http://www.visi1.org/cinelerra-gg_tutorials#CinelerraGGsThemes

In Cinelerra activate track mean Arm a track. The button is in the Patchbay (in the Main window). You can use Shift+LMB (Left Mouse Button) on Arm icon (button).

How to activate only one track? Does that mean arm track, or not to arm track?