I got a virus on windows 7, what to do?

I switched on my old laptop before, then I went into google chrome, then I wanted to check youtube and when I wanted something he suddenly opened any pages. (for example: internship, adac, job search.)

Have you thought about the Adware Cleaner? https://de.malwarebytes.com/...dwcleaner/

Had that too!

Try to install maleware bytes and or bit defender and scan

This is at best adware. How to get rid of, was already called. How to get: Software downloaded and unfortunately not the custom installation chosen where you can deselect such unwanted additions. Sites like Chip.de are notorious for offering adware installers. The alternative is usually linked inconspicuously.

I already have but brought me nothing.

Have you already run your virus scanner? Do not know which one you use? I use the IObit Malware Fighter 6 Professional.

I did that a long time ago but brings me nothing.

Bitdefender? How should one use this in a legal way without being allowed to pay at the same time?

I do not care: I have no qualms to get Bitdefender on Piratebay or similar:-))

If that does not work look in the task manager programs that should not be there and if that does not work I would reset Windows to factory settings