Assign 2 users to a ticket

So i have a situation where ideally i could assign multiple people to a ticket.
Im talking about 2 specific roles: Developer, and Tester.
I already have a field for "Responsible".
Ideally i could have another field where i could put the tester, and see both person in the list with all the tickets.

Now, the only way i could set 2 persons is in the detail tab, but i cant see them in the list of all the tickets.

I cannot find that setting. Can you tell me where exactly it is ?
Is it something new ?
Im on 11.4.2

It was on tab "Activity".

Last line there is "Manage accountable on tickets"