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Can you show a minimal working example? The bibliography header matches the rest of the headers for me. Just made a fresh download of the current version and added \setchapterpagestyle{thesis} to see the header on chapter starting pages.

Welcome to the forum, right now, we don't have any clue which document class you are using, nor which bibliography package you are using.
What package you are using for headers would be helpful as well.

Fontenc defines the font encoding, inputenc the input encoding.
utf8 is the standard on modern computers as well as LaTeX and does not need to be loaded specifically.

utf8x should not be used.

KOMA-script does not provide a class for presentation slides. If you need slides with pauses and overlays, simply use beamer.

Out of interest, what do you see when you try to go to texnique.fr?

I sent Stefan an email. Thank you.

Simply remove the biblatex package and everything related to it.
And read an introduction to LaTeX.

Crosspost on TeX.SX and goLaTeX.

Welcome to the forum.

Can you please make a complete example that we can test right away?

Package hologo.