As title.
I'm sorry, the translation may not be accurate, because English is not my native language.

What do you mean by “radio”?

Oh, broadcasts?

when I receive [message1 v]
broadcast [message1 v]
broadcast [message1 v] and wait

Right-click or click while holding the shift key on one of the broadcast blocks with the broadcast you want to rename selected. The block has to be in the scripts area, not the blocks palette. Then select “rename broadcast” (fifth option in menu).