Yes, well, if you insist on having an answer, I will try to give it to you (you will not be pleased, I fear).
This was last asked in 2014(!) with no responses.
That will be because there is no real answer, or no change mode IMHO in that sense.
…but not how to re-visit the complicated multi-tabbed dialog box…
I agree with you completely.
Now for my answer, which I am writing here as a comment so as not to upset anyone.
I assume that there is no change mode (I don’t know of one) because the process for new labels is very quick.
You just have to find the right brand and the specific label with its name.
But there are also some special cases where the user wants to create so-called custom labels.
I suspect it is your described problem regarding the “complicated multi-tabbed dialogue box” you refer to.
However, you usually only have to do this once for a user-defined label sheet.
In the dialogue itself you have the possibility to save the user-defined data of the labels and to give them a name.
The next time you create a new label, you only have to select this label name.
I cannot contribute more directly to this topic.
See also:
If it is a very important issue for you, you have the possibility to create a feature request on Bugzilla.