All sessions are closed when the device is turned off

First of all I apologize because I don’t speak English and I don’t know if I’m doing the right thing to ask for this kind of help. I use the translator.
My problem is that since 3 or 4 days ago when I turn on my computer I have to login to all my sites. This has been happening without me changing the settings.
How can I fix it?
Thank you very much,