Ok, it seems a page of replies hasn't helped because original poster has already "buggered it up" and admitted "doesn't fully understand how it all works".
Though I'm all for helping, I think, without direct intervention from any of us, there are two answers from
FAQs that will help this person start groups from scratch, and make sure Fadmin isn't causing some of the issue.
First tip - you can't add someone to user group. You can only remove people from other groups. Once removed from other groups, as long as you haven't broken user group in some way, they become user.
Second - See FAQ for resetting ULib/ULX to default.
https://forums.ulyssesmod.net/index.php/topic,5765.0.htmlThird - Disable Fadmin
https://forums.ulyssesmod.net/index.php/topic,5665.0.html