I didn't see the image in the folder you said to look, so I manually uploaded (ijfull_title2.jpg) it and tried to place it in again, but it still did not work.
I'm trying to stick to conventions too by not using file names with more than 8 characters in a string.
One thing I did notice about the gifs in there is that 3 of them won't open in Photoshop: ojs_home_title_default.gif and ojs_title_default and one of the pkp ones -- perhaps they are corrupt and that is why they can't be replaced. What would happen if I delete the ones that won't open? Will the sky come falling down?
The other wierd thing is that the image that keeps appearing, my original ugly blue tester image, is still appearing after I attempt to load my new title image! I'm looking through all the folders to see if it is hiding somewhere, but it appears to be a phantom image. (It is called ijtitle.gif or ijtitle.jpg can't remember which one I used, as I was going to load both and make a visual comparison)
Well I must say this is fun though. I'm very new at poking around -- promise I won't touch anything without asking first though.