Default [Q] Express999 rom - change settings background

Hi, I installed ipromeh's Express999 rom in my phone, which has a transparent background both in system settings and play store. When I change the background of my main window, the play store shows it on the background, but system settings still shows the original one. Do you know if there is a way to change it in system settings as well?
I'm new here and this is my first post, I didn't know how to contact ipromeh directly. Is there a way to do it?
Anyway, thanks in advance!