How to use User Group to restrict visibility of requests

How to use User Group to restrict visibility of requests

Hello

Need to fine control which requesters can see others requests. The is site manager visibility, department manager visibility, I know. But if we need more specific controll like users in FI group can see only FI requests whatever department or site?

I understand how to use User Group to control visibility of Incident Templates used to create an incident, that's all. 

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