Register YouTube on laptop?

Hey people my sister has a laptop where she also watches YouTube, she then goes to the browser, searches for YouTube logs in and if she closes YouTube, she is then no longer logged in

How can you change that?

There's a check mark "stay logged in" which must be activated.

But if the "hook" does not work, it will be difficult…

If cookies and other data are deleted when the browser is closed. That would explain this.

Depending on the browser, look in the privacy / data protection settings to see what is set there