I have the Firefox addon and I cannot find where the settings are - when I'm logged in to ebay the only thing I see is a Snipe link on the summary page ("snipe these") as well as a link on the individual item page ("snipe it"). In the Firefox Addon page there is just an "Options" button. I have not been able to locate a Settings dialog box as shown in the Screenshots on your site. Also seen in the Screenshots is what appears to be a summary page showing all the items set to be sniped, where multiple items can be managed. How do I find this? So far the only way I can manage to check or change an item to be sniped is to right click and "snipe this" again... it doesn't even show on the item page that I've already set up a Snipe. What am I missing?

Settings is a part of Windows application.
If you just need to manage the item, you don't need Settings or anything like that. All you need to do is to login to http://www.myibidder.com/ so you can manage your snipes (the same way as described on Mozilla website when you downloaded the add-on).