Complex sentence: All of the golden buzzers so far had been for a singer until week 6 of auditions when host Nick Cannon used his golden buzzer for Dorothy Williams, a 90-year-old dancer.
Split into simpler sentences: All of the golden buzzers so far have been for a singer. In week 6 of auditions, Host Nick Cannon used his golden buzzer for Dorothy Williams, a 90-year-old dancer.