Hi Kirby,
I will follow your earlier advice:
Recommendation
Reset all permissions after import.
Start over with Registered, give them all permissions every regsitered user should have and make every user primary Registered.
Add additional usergroups as needed any only set permissions taht are different from Registered.
This gives you a clean, easy to understand and maintainable permission setup.
But before I do that, I need to get my newbie head around some things.
I have highlighted some points of your earlier post, inside the following quote:
vBulletin
It is not possible to set permissions for an indivudal user
Moderator permissions are their own system, they can only be set to individual moderators - not per usergroup.
Admin permissions are their own system and can only be set per admin.
XenForo
It is possible to set permissions for an individual user
Moderator permissions are just permissions as all other permissions, just flagged as being moderative permissions - they can be set on usergroup level or for individual moderators.
Admin permissions are their own system and can only be set per admin, usergroups don't matter.
Aha, thanks to your explanations
@Kirby, it is starting to make a bit more sense to me. So, for me to get it further, I have yet another question. (Sorry for the overload of questions, but it has been more than 15 years ago that I properly made use of a vB admin panel and I am a total newbie to the XF one

)
When my vBulletin board got imported into my Xenforo testboard, I checked the
user permissions for the administrator (who is a Super Administrator). And I checked the
user permissions for moderators. Since I understood from your explanation that there are no individual user permissions in vBulletin available, I was wondering then how these would be set in Xenforo after an import.
I would expect that the user permissions for an admin and the user permissions for a moderator would all be set to “No”.
But this isn’t the case. See the attached PDF’s.
Moderator user permissions
For a moderator almost all user permissions are set to No, only a few odd ones are set to Yes, for some reason. So the moderator user permissions seem almost ok. (See PDF #3).
Question: I just need to set everything to No, I suppose, since I didn’t use any moderator user permissions on vBulletin (they don’t exists there and I didn’t need them, if they would exists).
Question: I just need to use Usergroup permissions for all my moderators, instead of setting any moderator user permissions, correct?
Administrator user permissions
But when you look at the administrator user permissions, a lot of these user permissions are set to Yes. They are all related to moderation tasks, as you can see in the PDF #2.
Question: Why is that? Are these Yes permissions somehow related to the fact that this administrator is a Super administrator?
You explained: “Admin permissions are their own system and can only be set per admin, usergroups don't matter.”.
Question: with this “own system” your refer to the following section in the AdminCP: [Groups & permissions, Staff, Administrators], correct?
Question: So, if usergroups don’t matter for an administrator (which is confirmed to me as a newbie by looking at the Usergroup permissions for the Usergroup Administrative, where I see that almost all permissions are set to No - see PDF #1) , then apparently what needs to be set (in contrast to the moderators) are the
user permissions for administrators?
Thanks for your time, much appreciated!
(I wish that there would be a consolidated help document somewhere overhere at xenforo.com that explains all these things).