If you are making yourself super admin in ulx, you should most likely make yourself super admin in the fadmin scoreboard as well.
If that doesn't work, and you have tried everything in the ULX Menu, I suggest using R-Con commands at that point. Just also note that some R-Con commands are blocked, but I am pretty sure you can do it. You can also do this command:
ulx adduser <user> or <steamid> or <userid> <rank> 999
That may help your situation, if not, then use R-Con, all you need to be is the owner, and you need to know your servers R-Con password, whatever you set it to.