When did KZZO transition to the Adult Top 40 format?
Reference
OpenAI's Answer
KZZO transitioned to the Adult Top 40 format in 2010. This change occurred when the station adopted the "Now 100.5" branding and began broadcasting as an Adult Top 40 radio station, a format it continues to maintain.
You can see an image related to KZZO's branding here:
For more details, you can refer to this source.