How do i make main menu slider adjust variable in different blueprint?

Hello so basically my problem is that i have a main menu where you can select a level, easy, hard etc and it will take you to an already built maze level. However, i want to have a slider that can adjust the size of my level. I have the variable that changes the size of the maze but how do i link them together? I have tried creating a custom event.

First Picture is what i’m trying to achieve with the level size. Second pic is my main menu event graph and the third picture is the variable i want to change in another blueprint called maze__gen_custom