passing variables on widget creation

In the image Above on Create Spell_C Widget you can pass a variable on creation, but I cannot get this to work in my version, seen below, how can I add this functionality in BP?

Properties of the variable you want to expose, tap that box

I have the same exact problem, thank you for asking it.

Expose on Spawn is grayed out for me when I try to modify the member variable.

I think I sorta figured out the problem: how do I make a custom component appear on Blueprint Components List. - C++ - Unreal Engine Forums