Unable to change Twitter Background? Try This!
If you are unable to change your Twitter Background, you are not alone! Numerous people have complained that they face various problems in setting their Twitter background. Some common fixes to these problems include the following:
1. Change the name of the background image file if you have already uploaded a background image with the same file name. If you do not change the name of the new image file, Twitter might assume that the new file is same as the old one. This trick worked for me!
2. If you already have a background image, you might want to clear it by pressing the button “Don’t use a background image” and press “Save Changes” to clear the existing background image. After this try to upload your new background image.
3. Try setting a Theme instead of a background image. After the Theme has been set, upload the background image (replacing the the Theme).
4. For other solutions, please read
Tried following your method; no luck still on getting the background to change.