Questions about quota users


I would like to set quota on my Gitlab server 12.10.11-ee pour all users. I’ve found information about “Size limit per repository” and “maximum namespace storage”.

  1. If i want to set user quota (including all project for one user) i suppose i have to set global "maximum namespace storage?

2)What would happened to already over-quota users? does it apply to new users created or does it apply immediately?
For example, if i set 200Mo in maximum namespace storage, does it take effect to users who have already used 150Mo (under quota users) or dos it take effect only to new user created after setting parameter?

What happened to users who are already overquota?