How do large companies identify users?

Question

User identification

Actually, how large companies such as Google, Yahoo, Yandex, Paypal, etc. identify users.
I heard about the Fingerprint method, which allows you to compare thousands of parameters and determine the user, even if he cleared the coockie and changed the IP, but I use the spere browser which allows you to generate unique parameters for each session , but they still determine me and ban me, I want to understand by what method determine.
Actions that I perform - Call the support services and download files on the site.
Maybe they determine by vote, but even if so, why are some requests approved and some not - about 50/50, sometimes the vote was not determined?)
Maybe I missed some details, tell me what else they can identify?
ps a call every time from a new number, I cleaned every cookie, I also take different ip every time.