You can upload a custom background for your issue  in the following way: 

1. From the My Publications page open the publication you wish and click the Edit Settings https://cdn.elev.io/file/uploads/Nx6j1ilgYkjKwwUzxKv9Jx2yWyIGUZG4VbEE9W71H30/NezJcSiVyGhqDjZyVBlvF_2UJXfeBUd-tKhnV6KhAu4/edit-settings-t_8.png button of your issue. 

2. Go to the VIEWER tab and click browse

3. Choose the image you want and wait until it finishes uploading.  

That's it! Now you can apply your custom background. 

Note: This option is available only with our Premium plans.