C# How to make one item from Menustrip be default selected?

Question

 
I am working on C# WFA. I have one menustrip which has one item called: Settings, under this I have three items: ID, Number, and Time. Under Number item there has 5 items again which man can choose. Now I want to make it like this: first make one of the items under Number is default chosen, Secondly, I want to have one more textbox in the GUI, which will show which item is selected under number.
For example:

       Settings

               ---ID

                ---Number

                    ----NUMBER1

                    ----Number 2

                    ----Number 3    

               ---Time

So I want to set the Number 2 as the default chosen item, how can I do that? I want to display the selected Number item in textbox when one is selected, How can I do that?
Thanks a lot!
BR Emma