[QUES] How to make one UserControl effect something in another UserControl (WINFORMS)

Pretty much, I want to use UserControls to create tabs like Settings, Main, Game Hub, ETC. How would I select something from the settings tab edit the Main tab, I know how to make multiple apis using normal but like Select a RadioButton in Settings tab and then that selects the api that you use. I just gotta make when you click something from the settings tab edit what happens in another UC.

Thanks.