Meanwhile I have many running apps in my phone and I found that a lot of apps keep running because they "trick". They register as a boot receiver so they start with the phone, then register as a "new app installed" receiver and so on. The do everything to keep running. If you kill them, some of them start again because the creat a service which checks if they are running. I guess these apps do that because they want to transmit information about the user or phone.

What can I do against those apps when the phone is not rooted? The task killers that I checked do not work. I think they are fake.

(With a rooted phone the Autorun manager seems to work good)