Please post an active link to the blog in question starting with http://
Then we can visit your site and see which them you are using.
Please also post active link to the posts, page and/or image in question when you post to the forums so we can examine the same. Until we can get some details here we cannot even begin to help you.
my uploaded images show on my site for a min or two after uploading then updating, then refresh my site and the image has gone.
This sounds like a browser issue to me. Please try clearing your browser cache and cookies. If your browser version is out of date then please upgrade it here. If those don't work for you there are other troubleshooting techniques that can be employed.
What is creating a custom excerpt about n what is the excerpt module?
This is the main link
to all support documentation. Here is a link to the excerpts
entry and Splitting Content » Excerpts