Header image URL doesn’t update with site adress

I've added a custom header image for my front page. Viewing the site on my server looks allright. However, viewing the site on another computer the header image is not shown. When I look at the site code I can see that the header image is referring to 127.0.0.1 local adress, meaning any external computer will not find the image. This is strange since I changed my wordpress settings for the site adress to be 192.168.1.64 which is my server. But for some reason the header image doesn't recognize the site adress change. How can I make sure that the header image follows the site adress?