How Security Group works with role?

Secnario:
User A and user B report to manager C.
User A has account A1 & A2.
User B has account B1 & B2.
Manager C has acocunt C1 & C2.

What I want is user A cannot only see his own account A1 & A2.
User B is the same, can only see own account B1 & B2.
Manager C can see all of ABC’s account: A1, A2, B1, B2, C1, C2.

How to address this?
I have a user group G1 with user A, B, C in it.
I have create a role R1 with the the Account List privilege set to Group, and add G1 into Security Groups Manager.

But after manager C logon, still cannot see user A and B’s account.

How can address this? Thanks very much.

Have a look at this, it’s quite similar to your needs

https://docs.suitecrm.com/user/security-suite-groups/#_a_typical_hierarchy_setup

Normally, the step that everybody forgets to do is to assign the records themselves (not just the users) to the security groups.