Moving UI elements not saving?

Hey everyone. I'm trying to move a UI element that you can't find in the HUD layout, but no matter what I do it always goes back to it's previous default position.

More specifically, when you click to desynth an item, a desynth window pops up, where you can check or uncheck the box next to "desynth entire stack." This window was originally at the center of my screen, but I moved it to the right to a new location, and now whenever I click to desynth an item, it's new default location is on the right where I placed it.

However, the problem comes from the fact that now, whenever I try to move it again to a new location, it will not change it's default position. Instead, it keeps appearing on the right where I moved it the first time.

Is there something I'm just not understanding? I would like if I could either move the window back to the original default position (center of my screen) or be able to save it to another default position.