Does it matter if you sit or lie down? I find my back hurts when sitting in easy pose and I tend to end up leaning too far forward or back. I find myself swaying

I think it's better to sit upright, to your column get used to the right position. I tend to sway when I've been sitting for a long time too, but when I notice I try fix it, because I know it's not healthy for me. Just try to fix it whenever you notice. The results will come sooner than you think