1. What did I do?
I wanted to create a parametrised blueprint where you select the respective "Fill X barrel" recipe signal to be set in a decider combinator, which was supposed to set the assembler's recipe.

2. What happened?
When placing a parametrised blueprint for a fluid voider I select any ...

As this is apparently not a bug, what do I do with this post now?
Do I delete it or move it to the "not a post, it's a feature" and if yes, how? ^-^"

That's exactly the problem.
They ARE all unlocked in new worlds.
Or is it on purpose so that it is counted for the whole game and not separately for saves?

I generated a world in 0.17.0 which had only the ALT-mode unlocked in the Quickbar.
Then I loaded an 0.16 save (with 0.16 creative mod which got removed while migrating) which before had every research unlocked (after loading it also had all Quickbar features unlocked.)
When I got back to my 0.17.0 ...