Only the administrators can set the permission for the custom reports.
How to set up？
Website
1. Go to Project Administration > Custom Reports
2. If your project has multiple custom reports, choose the one you would like to manage access from the drop down list.
3. Select the user(s) you want to manage access, and move the user(s) to "Available Users" or "Assigned Users" via 
or 
Please note that the system will not automatically set the newly added user to be able to view custom report(s). Don't forget to give new users access for this too when you create a new account.