Why I was wary of joining the thread? Because I'd like to be able to use the site without site questions being sprung on me (which is more like work than having fun here most of the time) on threads that aren't about the site. And also because I don't know if I can answer the voting question any better than the last couple dozen times I have (not all to you of course) so I feel like a broken record. Also, I think sometimes it's not really a question, but a complaint that isn't ever going to go away. So it feels like being nagged.
But as to the tech part of your question:
"History" is a list of urls you have visited. Your browser "cache" is a collection of files (images, etc) so that you don't have to download them again.
Clearing your cache to check every time would be a bit cumbersome and make your browsing slower. I tend to use a plugin (web developer toolbar, which I don't really recommend for non-developers) that allows me to temporarily disable the cache but the easiest solution for you is to use something like imageshack's transloading. If you already know how to use imageshack uploading it's just as easy. Choose their "URL" option and just paste the url that you would have posted here there, and they'll get the image and store it and provide you a new url to post.