Proper access to the project and some "time estimate" functions?

Question

JIRA

Good afternoon.
I wanted to clarify how to properly set up project roles in jira.
I have:
developer;
designer;
sysadmin;
I want that only the developer could get into the project, and not everyone else.
So that only the administrator can set the time estimate, and not everyone.
I added project roles, everything seems to be set correctly, but the developer can edit the fields, and the system administrator sees other projects. Please tell me how to organize this scheme.