Hello,
Sorry for the inconvenience caused. Actually, with some of the Demos there are certain Custom Layouts enabled for the Single Product and Archive pages which is why your made changes under the Theme Settings aren’t taking effect on that.
The Layouts can be found under the Dashboard > Layouts. For the time being, we have disabled the Single Product layout too on your Site and you can now make the changes through Theme Settings on that.
Further, you can read more about the Layout Builder for Single Product here on the following Theme Documentation guide:
https://xtemos.com/docs-topic/single-product-page-builder/
Best Regards