Ok, what I found:
Using other browser I tried to see headers. And using test user, I changed his usergroups to have access to different parts of forum.
Anyway, this is very confusing and it looks to have some link to my report that headers after upgrade aren't visible. After I checked for headers, they become visible. At least to me. But now I don't know who actually could see headers and who couldn't.
For example, as my test user I tried to see header created by my admin. And I couldn't see it. After I went to headers forum (were headers are placed), and entered there this header and choose to see header in context, now I see header. Before that, I couldn't. This is same as explained in report about problems with headers after upgrade.
But, main thing is, who can see headers? Maybe some do, maybe some don't. Only certain users could go and see header forum. Also, I couldn't reliably tell if others see headers if I see them. Because I had this certain header visible with my other browser and my other account (main one, not this test one).
So, even if I make header visible to me, it's not necessarily visible to others.
And it may even have something to do with cookies.
About my testing with mod to log in others account, I think we may disregard these results. But, testing with my clone account, this is very strange and very confusing, I see some headers, some don't and I don't see same information in all of them, but I should (I mean the thing with edit link in two forums when I looked at them as registered user, as reported in previous post.
The most upsetting thing is this difference between what I see, what I don't and unpredictability. It seems like everything changes with every pageload. I'm not sure why, but things are changing.
