Changing flag and president images

I have tried to upload my president image and flag across my countries. I can do it on the ones that did not have something previously uploaded. For the ones that already had an image from the past player, I can't seem to change the images. Is there something I need to do to remove the old images first?

I had this problem. Not with the flag, but with the president. Basically, just wait. It took a few days for the change to be visible for mine. For whatever reason, the change was visible on mobile, but not from my menu in the game. If it doesn't give you an error, it may just take some time.

Try clearing your cache.

Clearing the cache worked. Thanks EO