How to enable lock icon

[Cosmic11]

S7 nougat states that you can lock an app into the recents section thereby when closing all apps it stays open, so you can return to it easily.... I do NOT mean the pin app..) But the lock icons are not on any of my apps when in recents list? Please how do I get them or is there an app that will do the same.. Thankyou

 

[Golfdriver97]

I would guess it applies to Samsung only apps?

 

[Cosmic11]

I would guess it applies to Samsung only apps?

it states it is all apps here like thishttp://www.techrepublic.com/article/how-to-make-use-of-the-android-nougat-recent-apps-lock/