Hey there Andrea,
Sometimes even with premium products you’ll still have to use some CSS in order to get it just the way you want and in most cases extra customization options are usually available in premium version of themes (not sure if it is included in this one since I’m not representing theme authors).
With that being said you can change the color of the widgets by adding the following CSS code to themes custom CSS tab which is located in Appearance -> Customize -> Theme Options -> Advanced -> Custom CSS:
.sidebar .widget {
background-color: #f1f1e5;
}
Replace the color hex value with the color that you want. You can use sites similar to this one to get hex value for the color of your choice:
https://www.color-hex.com/
Hope this helps ??
Cheers,
Bojan