@Frenz75 @Iain_B I think I fixed it! It turns out the style of the control center was the issue! I'm using the old one. (I also use the launcher style with the drawer.) I switched to the new control center style, I edited the icons and rebooted. They stayed. Then I switched the style tothe old and rebooted. They stayed again! From the results it seems like if you want to do a "permanent" change to the those settings/icons (is it called quick settings?) you ~have to switch tothe new control center style, do the edit (reboot maybe) and change the style to the old one.