I'm trying to customize this form, but I can't find any way.
Can you give us idea what kind of customisation you need?
1) Visual appearance? Your own CSS style.
2) Custom fields to the form?
Yes the visual appearance, in order to use my own CSS and make my design smoother.
Hello Sergey, any news about that?
You cannot customize modules for this form, because it is common form for all projects.
But you can customize CSS for this form from your project settings->Project->Custom CSS->Widget.