How to customize the quote picture?

I wanna replace the quote picture in the quote block. I had changed the quote-blue.png in the image folder. But it doesn't work. Please help me~

 

Please check whether you have selected blue color css through styling options or not.
If you select blue color then only quote will change.

 

Hi, the quote picture was updated. The thing is every time I have it changed, it takes a while for the serve to update. It is a little weird. Is that normal? Thanks, Nitesh, you helped me a lot!

 

Please do let us know your website link.