Why Isn't My Header Changing on Twitter?
Click the "Profile" Tab on the Left, Then "Change Header." If This Button Doesn't Appear as a Drop-Down Menu, You Don't Yet Have a Header Photo. Otherwise...
Click the "Profile" tab on the left, then "Change header." If this button doesn't appear as a drop-down menu, you don't yet have a header photo. Otherwise, click "Remove" to delete your current header. Twitter automatically replaces it on your profile with a default black texture.
How do I change my Twitter header?
Sign in to twitter.com or open your Twitter app (iOS or Android). Go to your profile. Click or tap the Edit profile button and you'll be able to edit your: Header photo, also known as a “banner” (recommended dimensions are 1500x500 pixels)
How do I fix my Twitter banner?
The Solution: The fix is really simple. All you need to do is to take the final header image and adjust the opacity to 99% and save it as a PNG-24 file. By giving the image some kind of transparency, Twitter is forced now to save it as a PNG on the server instead of a JPEG. JPEG's can't display transparency.