SuiteCRM - Groups/Permissions

Hi guys- I’m new to SuiteCRM and am loving it so far.
However I wondered if anybody could help with the following.

I have 3 teams using SuiteCRM; Team1, Team2 and Team3
I need to assign accounts and contacts to one of the 3 teams only and ensure the other teams cannot see these.
Essentially teams should only be able to see accounts and contacts they have permissions on.

I figured this would be part of the Security Suite Group Management but I cannot get this to work.

Any help would be greatly appreciated.

Thanks, G