@Hyncharas - you can set the real-time resolution on the Project Window, Image tab. When you go to Render, the Sill Image resolution will match the aspect ratio you've set in the Image tab. If you change W or H here, the other will update. You can also choose a preset.
@ Glen_Powis - How big is the file you're uploading. There is a 50MB limit. If you're uploading multiple, you may want to try one at a time. If you're still having trouble, just email them to web@luxion.com.
Thank you.