Find your client, then select "Settings" and choose "Manage Access"
If you need to limit access to the other team members, you may manage to hide specific client, ie add the names of team members that you want to give the access.
If you added at least one user, the said user will be able to see this specific client. If none were added, this client will be visible and can access by everyone in your team.
Be sure to have reviewed How to Invite Team Members
Other way to manage access, press "Clients", choose either "All" or "Clients", then click the little lock icon. It will take you to the "Manage Access" settings.