If a company level user has access to multiple companies and have been linked to different security roles in each company, how can the the permissions linked to each security role be applied in each company?
If a user profile is linked to multiple security roles, access will be allowed as specified in the security role with the least amount of access across all companies the user has been given access to.
Enable the following checkbox on the Security Settings screen to apply each linked security to its respective company.
Navigate > Configuration > Security > Security > Security Settings