You can customize your individual profile, including your cover picture.
STEP 1: Click on your name in the top right corner
STEP 2: Go on your profile
STEP 3: Click on the icon on the top right of your banner.
Click on the cross in the top right corner of the image to delete it.
To add a new one, after you deleted it, just click on the “+” and take the image you want from your computer.
That’s it! Now you have a new cover image!