Hi there

By default for ERD shapes when you select "Shaded Header" from the Advanced Options menu the shape's header will be filled a light grey. It is not possible to change just the color of the shaded header. I’ve added your post to the product feedback community page to suggest this feature to our development team. Everyone who would like to see this functionality, please voice your support by upvoting the post!

There are some workarounds you can employ. You can change the color of the header by changing the fill color of the entire shape. If you do this the header will still be slightly darker (i.e. if shape is light blue header will be dark blue).

Another workaround would be to create a text shape delete the text change the fill color as desired and make the shape opaque and place this shape over the header which will give the shape header the color you're looking for. 

Thank you for your request and hope this helps!