menu do not save

Dear GeneratePress,

good morning,

I would like to kindly ask to you about a problem I am having with saving changes to the widget-menu:

the first strange thing I noticed is that once I entered the personalization area, add widgets (vertical menu) to the left bar, it asked me if I wanted to continue viewing the widget management in a classic way or in a new way, I chose the latter and I don't know how to go back because:

A) the menu-widgets, open very slowly
B) if I modify and public does not accept the modification and does not save

Thanks for your attention.

Sincerely.

RaTve.it