Hi everyone. I'm sorry. I can't reply any kind of thread, just post in this category.
I saw a lot of people needed to change the proportions of the cover, like i needed to, and i finally figured out how.
For Jomsocial 3.2 just write this on your principal stylesheet on the site, or any you can change, to overwrite the one from Jomsocial template. This way you could upgrade Jomsocial without loosing the change. Replace 25% for the percentage you need. It's an easy and quick solution, and it worked for me in Google Chrome and Firefox: