Thanks for both answers - I am seeing it as admin and you are right I can't see it otherwise. However I still can't see how I could control who sees this - from the studio > pages > persons > view profile > go to the block "info" and chose the visibility option it looks like it just controls who can see all the items on the Info rather than how I control the IP setting. Most options have controls but IP and a few others don't for some reason?
This is the field filled automatically by UNA, so any changes there may affect the proper work. That's why it is closed by standard admin's editing. If you have something extremely necessary to correct from your point of view you may use Developer app (Studio->Developer->Forms->Persons->View Profile area).
I use this field a lot, it's well designed. Sometimes some doubtful accounts are created successively, a simple click on the ip address of one of them reveals to me the other accounts created from the same ip which confirms my doubts and moreover it allows me to do the cleaning quickly in an operation. Really a good point.