The reporter keeps changing when I move issues between projects

We are currently using JIRA to track and manage defects raised by multiple teams. Each team has a JIRA project - and users are generally permitted to raise issues within their own projects. Issues can be moved between projects to reflect whoever currently has responsibility for each particular issue.

When an issue is moved between projects the reporter changes (for some reason). It is important for us that the reporter remains the same irrespective of which project the issue resides within.

I would appreciate any help or explanation that anyone can provide of why this is happening - and how to stop it happening. As I cannot seem to determine the problem / solution by myself.