I'm so frustrated... I changed my logo and it worked great. Now I want a new logo with some colour (didn't have time last time) and for some reason, every time I upload the new header, it reverts to the old one.

Things I have tried...
1) Deleting the old file, then uploading the new file
2) Changing the permissions to 777 on the old file, then uploading the new one with a different name and then re-naming it to the original header name.
3) Using Filezilla to FTP the image and over-write the old one
4) Changing the new file to permissions 777 and then re-naming to the header file
5) Uploading new file same name as header and over-writing it

Nothing seems to work... what am I doing wrong? HELP!!!
I'm sure it's simple and I'm just not getting it...
Thanks in advance :)
Kendra