Hi and welcome!
are you talking about custom modules/fields? If you update the “assigned to” user, the change should be visible immediately, both on the UI and the database.
So, are you using factory modules/fields, is there any additional logic (like hooks that also set the assigned user)? Is the problem just the visualization or can you see on database level too that your change is not saved?
Please also be careful about the wording, e.g. “account”: do you refer to the module to store companies or user profiles?
If i update ‘assigned to’ user of any other group (B) then it should not visible to previous group user (A).
problem is just the visualization means UI level i am checking.
change is saved but lead assigned to one group to another group then previous group user should not view it in their leads.
Note: Assigned user field in leads is displaying updated new group user.
In that case, could you not use combined security groups.
Team Role - set to owner
Manager Role - Set to group
For each manager create a security group for there team.
This means that manager can see any of his teams records, his team can only see their own records and then if the managers personal leads are assigned to another manager in another team then the old owner cannot see them.