I know the default in inkscape is a transparent BG, but my backgrounds are (and have always been) white. I'm pretty sure it's set as transparency as a background too.

Help?

Welcome Lovely Rita!

Ok, the background looks white, but it's really transparent. You can confirm whether it's truly transparent or not, by opening File menu > Document Properties > Page tab. In the top right corner is a place to set the color and transparency of the background. There's a bar there, beside "Background:" If it's set for white opaque, you won't see the bar. But if you click on it, you'll realize it's there. If it's transparent, the bar will be filled with a checkerboard pattern. Or it could be partially transparent, and you'd still see the checkerboard. So to confirm it, click on the bar, and a very small window will open. The A value should be 0, for full transparency.

I you prefer to have a checkerboard pattern on the canvas, you can draw one. Then save it as a new default template. Personally I find the checkboard annoying. It's one of the biggest reasons I prefer Inkscape. But I guess some people have become accustomed to it. Anyway, let us know if you want to make a custom default doc, and we can tell you how.

If the problem is a white background when you save as a PNG image, make sure to use File > Export Bitmap and NOT Save As... Cairo PNG.

@Xav figured that out AFTER I submitted this. Thanks.