Please see below for the number of users who can sign into PlayStation Network simultaneously on the same PlayStation system:
Only one user may sign into their account on PlayStation 3, PSP, PS TV or PS Vita systems at any one time.
Although up to four users can sign into PlayStation Network on one PlayStation 4, you may only use SEN account features on one account at a time. This account is shown at the top of the screen.
Any other accounts remain signed in in the background. This means that any game progress* or trophies won by the signed in accounts are applied to those accounts.
To sign in a second, third or fourth account on a PlayStation 4:
If the PlayStation 4 is not already activated as your Primary PlayStation 4 you will be asked if you want to activate it. If you are using someone else’s PlayStation 4, select ‘Do Not Activate’.
*Provided the user is a member of PlayStation Plus.