Trouble changing background images and color

Hello, we are trying to set up a site for a client but we’ve come across an issue.

We can’t seem to change the background image or background colors for the site. At best we will see the image flicker or the color flicker for a split second when you refresh a page but afterwards its white. We already tried clearing caches and we also tried viewing the site on several browsers and we still get the same flicker effect.

We are use a wordpress theme called glammy. and this is the site at the moment mdand3hatcompany.com

Any idea on how this can be fixed? If there’s more information I need to post let me know.