Change size of background on iPad

We are using iPads and unless I add layers, which I don’t want to do, the additional backgrounds are very small in the right hand corner.
Does anyone know how I can make it cover the entire screen? I can not find an “advanced tab” in options while using the app on iPad. And I can’t use higher resolution pictures.
Any help would be greatly appreciated!

Hi Jessica,
Can you email a sample project to What background are you using that is having issues?