You can get started with system or PlayStation Network features quickly and take advantage of remote download if auto sign in is set up.
However, this means that your account may be easily accessed by others who can use your PlayStation system. Therefore, there are certain situations where you should not have auto sign-in enabled.
There are two accounts that you can sign in to on your PlayStation 4; the local user account, which is the user on the PlayStation system itself and the PlayStation Network account, which can be linked local user accounts on different activated systems for playing online, making purchases from PlayStation Store etc.
Signing into this option alone (i.e. not signing in to PlayStation Network as well) means that apps cannot be launched. This is because users must be signed into PlayStation Network to launch any content purchased from PlayStation Store.
If there is only one local user or, if [Log into PS4 automatically] is enabled on one of the local user accounts, the PlayStation 4 will automatically log in to this user when it is switched on.
To switch off auto log-in go to [Settings] > [Users] > [Log In Settings] > [Log into PS4 automatically] and un-tick.
However, this does not stop others from manually choosing to log into the PlayStation 4 on your local user account. To limit access to your local user account, apply a PIN to it on the Log In Settings screen so that other users cannot log in on your local user and find out more about PlayStation 4 system sign-in controls here. This will ensure that if you forget to sign out of PlayStation Network other users will not be able to access your account.
The PlayStation Network account assigned to the local user account cannot be changed after it has been chosen. Once your local user account is signed in to PlayStation Network, it stays signed-in in the background and automatically signs back in when your local user logs into the PlayStation 4, even if the system was switched off completely.
This means that any user with access to your local user account can also access your PlayStation Network account information and any content that has been purchased by any other local user on the PlayStation 4.
Sign out of PlayStation Network at the end of every PlayStation 4 session to stop others accessing your account by going to [Settings] > [PlayStation Network] > [Sign out].
Your PlayStation Network sign-in ID is retained by the PlayStation 4 system so you do not need to enter it again, but you cannot set up the system to remember your password too, so signing out will stop anyone who does not know your PlayStation Network account password from signing in.
You should sign out at the end of every session on your PlayStation 4, but be extra careful if any of the following apply:
If you do not have access to your PlayStation system to sign out of PlayStation Network, you can change your password from a web browser. This means that if another person has possession of your PlayStation system they cannot access your account through it, even if auto sign-in or saved password is switched on.