In my style file, I have:

\RequirePackage{fancyhdr}
\fancypagestyle{plain}{
  \fancyhf{}                              % clear all header and footer fields
  \lhead{\spaceskip=5pt Custom Header Name}
  \cfoot{\thepage}
  \renewcommand{\headrulewidth}{0.5pt}
  \renewcommand{\footrulewidth}{0.5pt}
}

But I like to configure it from my documment file... I mean, I like to specify the argument of \lhead in the tex file. How can I do it?

Today is a good day to follow @DavidCarlisle reading tips, so I'll entertain myself by reading LaTeX News 34 :D ... Happy Father's Day to everyone

@DavidCarlisle Yes

@JosephWright I added some text to the title and asked it to re-check but google decided it's an error page that should be served as 404 not 200. They don't suggest any way of telling them that isn't the case other than changing the text or serving it as an error page.

@raf just use \lhead{whatever} in your document?

@DavidCarlisle Tricky - this must be a known issue

@DavidCarlisle Which page is it?

@JosephWright texfaq.org/FAQ-normalszmiss

@DavidCarlisle what is the problem? It seems to work fine here.

@UlrikeFischer that is the problem. Google heuristics decided that is an error page that should be served with an http 404 status not a success 200 status, so it is flagging the site as failing in the google search console

@DavidCarlisle you mean one can't search for it?

@UlrikeFischer you can search but some google features are blocked and (probably) the google rank is affected, although they don't say exactly what the consequences are.

@DavidCarlisle yes, like that. How can I do it?

@raf no I meant literally do exactly that, put the line \lhead{whatever} in your document if that is what you want to do.

@DavidCarlisle Sorry, I didn't understand. Right now, I am keeping the fancypagestyle setup in a separate sty file. It's not working if I insert just \lhead{whatever} in main tex file!

no reason why it shouldn't work (although \lhead is the deprecated old form of \fancyhead[L] it should work the same way) as ever, better to make an example and ask a question on the question site rather than in chat with no example:-) @raf

Okay, I will make an example

What's the easiest way to recreate the Unicode symbol "❙" in pdflatex?

(a vertical bar of middle thickness)

ah, tex.stackexchange.com/a/520904/38074 is good enough

@UlrikeFischer does biber have documentation?

@DavidCarlisle you could also check the source code -- all in perl.

@UlrikeFischer why can't the package define \zz to be the font and let the user use \zz{BQP} rather than defining every one two and three letter combination as a \BQP to do the same thing setting the command name in the font chosen?

@DavidCarlisle probably because of the variants like \ComplexityFont{Mod}_k\ComplexityFont{L}, or because he wanted to get an error for typos like \zz{BPQ}, or because the author didn't know \csname.

@UlrikeFischer is that clean option there by default or has the OP added it?

@DavidCarlisle it is there in miktex, texlive doesn't have this combination. (it is like the update topic, I saw that already more than once).

@UlrikeFischer why have "make cross references never resolve" as a default behaviour?

@DavidCarlisle well it is actually texify and it is like latexmk, if does more than one run and so does resolve the cross references, see the picture of the OP, there is "section 2". But the next time you call it you have to go through the whole lot again. (The real question is why using texify at all, imho it is a pain).

@UlrikeFischer not sure I underand how that \ref doesn't resolve then if it dous rm*aux pdflatex makeindex pdflatex every time it would be slow but work?

@DavidCarlisle I don't understand it either, I suspect that there is a bug in texify and timing is wrong, but I didn't care enough to investigate, I simply tell people to remove the clean option and this cures the problem.

@JosephWright @UlrikeFischer ^

@DavidCarlisle what did you do to convince google?

@UlrikeFischer just added some more words so the percentage of words that were "error" decreased so google decided it was a real page. Not a very exact science.

@DavidCarlisle Yay

@DavidCarlisle Hi, sorry, I wasn't here really. I don't see how that interacts with us direclty? Was the class updated officially, or do you suggest we tweak the template around a bug that's in IEEE's code?

@yo' you must at some point(?) make a decision about which classes you make available that aren't in texlive. Making available ones that are fundamentally broken isn't really your fault (you can't be expected to vet them all) but they could do with a health warning since the publisher unlikley to fix it) but my threshold for moaning to you and Paulo here is a lot lower than it would be for making an actual change request to Overleaf, so feel free to ignore along with general chat here.

@DavidCarlisle similar here regarding the "process": I wouldn't get into an open-ended discussion with anyone on official support :-)

moreover, that template doesn't seem to be provided by us, so it's complicated

oh it is, actually, provided by us, so we can do some changes to it :D

@yo' trouble is if you change it too much you may find documents work on overleaf then fail when submitted to the publisher. So in a way it's probably better to leave the class as is and tell the users to put a fix in their documents. Or just keep your head down and ignore it:-)

@DavidCarlisle or prod the publisher about it. We've definitely done that before, playing the bad boys, so I'm free to do it again :D I'll put it on my list

anyway, I'm off now, see ya!

@yo' thanks, maybe you have more "clout" with the publisher, I've more or less given up trying to get publisher classes updated I have tried three or four times now (not that one) and nothing happened with any of them.