This is usually because of two main reasons:
1) You need to do a hard refresh
Your old header image can become "cached" on your computer. This means that your computer will keep serving you up the same old image, rather than going and getting the new image.
To fix this, you just need to do a "hard refresh". Click here to see how to hard refresh.
2) You didn't click "Save Settings"
After you close the header creator there is another button where you need to confirm the new header settings. If you watch this video lesson you'll see how to do that.
If neither of these work for you, or if you're getting a specific error message, please contact our support team using the link below.