I am having trouble figuring out how to work with the Alpha Channel in Affinity Designer (v1.7.1). When I export a graphic from Designer as an image file and then open that file in an program like GraphicConverter and flatten it, the background is black. In all other drawing programs I've used over the years, this same process results in a white background.
I have looked through forum posts and web searches for tips on how to work with Designer's alpha channel, but I have not been able to figure this out.
Is there a setting in Designer that can make the alpha channel always appear white instead of black? If not, how do I change the alpha channel from black to white for each file I create?