How to make changes to the site header in TYPO3?

Question

CMS

Own subject.
As usual, this is done on unfamiliar systems:
Set grep on the site files and look for occurrences of what needs to be changed. We change. We rejoice.
In this case it doesn't work - found all occurrences (they are in html files in /fileadmin/template/ ). Made changes. Nothing changed? Cache? But this data is not in the cache files. Cache in DB O_o? I went to the admin panel, cleared the cache.
Nothing changed.
I found this article https://kosenko-danila.livejournal.com/7917.html
I don't have any sign with a Page header, but there is a sign with the
Storage Folders column and there is also some path in it. If you click on it - a page with a structure and there are Update mapping links. Pushed them. Cleared the cache. Also no effect.
How to make (apply?) Changes then?

Answer 1

Typo3 templates set the markup inside the tag
The rest of the settings are set through the settings: TypoScript
and In good manners, write the Typo3 version and what exactly you want to add