It's possible to differentiate access to CRM companies. Let's say that Sale Manager should see only his/her companies and not others.
There are steps to make such settings.
- In CRM Administration, tab Companies create a new company attribute with JIRA user (or JIRA Group) type, for example an attribute "Sales Manager". See more: Set up Companies Directory#188.8.131.52SetupCompaniesDirectory-SetupCompanyAttributes
- Restrict CRM permissions depending on that attribute. See there: Setting up Access to Objects
- Open a Company card and set the attribute "Sales Manager" with needed JIRA user/users (group/groups).