90sAnimeFan said:
I foolishly uploaded a picture without checking to see if there was a better quality one, and now it seems I can't change/update the image even though I changed the source? post #2949103
You can't change the image by changing the source. That's just metadata. Images must be replaced instead, which only certain users can do.
Therefore, to change the image, request it be replaced in topic #14156. Include the post # and a link to the better quality version.