Hello there,
First of all, sorry for a late reply.
I am afraid to say but you are not completely right. Yes, the image cannot be changed from the Front-end or back-end editor, but the image can be changed. See the screenshot.
As the image is completely loaded from the core code, you need to change it from here. The path to the folder is - templates > finion > css > template.css. From there, you can change the images from there. See the screenshot.
To know which images are there, please go to templates > finion > images. You can even add images there if you want to.
I hope, you can understand now how to do that and it helps you to solve the issue. If so, please close the post by accepting the most accurate answer so that others can get the solution easily.
Thanks!