Steemit has implemented image cache to speed up image retrieval and display.
Unfortunately, this cache mechanism prevent the images to be dynamically updated.
I opened a github issue to ask Steemit's devs to implement a cache bypass, but didn't get any response up to now :(
Meantime, you have to manually build your own footer
Thank you for the info, @arcange. I wonder if I should continue to use the correct links after all and not build another footer. The info might be incorrect now but probably corrects itself later if they ever change it. But then I cannot go back anymore and change my footers in older posts.