To configure which fields are editable in the "Create Issue" dialog, do the following as OTRS administrator:

1. In the OTRS dashboard, select the Admin tab.
2. In the Admin tab, select SysConfig in the "System Administration" section.
   
   The "SysConfig" dialog appears.
   
3. In the "Actions" section, search for jira.
   The search results are displayed on the right.
   

4. Select CreateIssue in the list of search results.
   The following dialog is displayed.
   

5. In the "JIRA::SendReporter" section, select Yes make the user configured in the "Reporter" field in the REST configuration dialog as reporter of the new JIRA issue. Otherwise, select No to hide the field.
6. In the "JIRA::ShowProject" section, select Editable to make the JIRA project editable in the "Create Issue" dialog. Otherwise, select Hide to hide the field.
7. In the "JIRA::ShowAssignee" section, select Editable to make the JIRA assignee editable in the "Create Issue" dialog. Otherwise, select Hide to hide the field.
8. In the "JIRA::ShowAutomaticUser" section, select Yes to display the automatic user in "Assignee" field in the "Create Issue" dialog.
9. In the "JIRA::ShowIssueType" section, select Editable to make the JIRA issue type editable in the "Create Issue" dialog. Otherwise, select Hide to hide the field.
10. Click Update to activate your changes.