For a while, I cross stitched a new nerdy quote and framed it as a gift for my brother every year for Christmas. I worked hard on them. At some point I realized that I could single-handedly be responsible for filling his walls with decor, and decided I should probably lay off. But there were many years when that was my brother-craft.
Unfortunately, at least in part, I did it wrong. I recently learned that there's a way to prevent the ugly wrinkles that my projects were plagued with. He recently moved away across the country and I can confirm that the knowledge that I could FIX those wrinkles but can not because he's living so far away is definitely burning my brain.
Pictures are less than ideal because OF THE WRINKLES and also because I didn't take any photos of them myself, and instead asked my brother to take nice pictures and I'm not sure he knows how to do that.
And I also did a set of three quotes from Firefly!
So the way you fix the back is to back the cross stitch with some cardboard, and then stretch sew it into place!
You can find a good tutorial for that here: https://peacockandfig.com/2016/01/how-to-frame-cross-stitch-embroidery/