Number of sub-pages display in the sidebar

Hi,

i’m using the right side bar to show posts or pages https://www.espedia.it/espedia-live-2-2/

I can i reduce the number of pages shown?

The widget seems to not permit to set a number limit and i don’t want to select the pages i want to diplay every time, manually.

Moreover, how the page visitor could go back to previous pages?

Thanks