If you share a fatwa and it changes, no need to update others. But if you shared it wrongly, you must fix it.

Practical Laws of Islam as per the teachings of Ayatullah Sistani

Ruling 11

If someone relates a mujtahid’s fatwa to a second person, in the event that the mujtahid’s fatwa changes, it is not necessary for him to inform that second person that the fatwa of the mujtahid has changed. However, if after relating a fatwa, a person realises that he has made a mistake and his statement will cause that second person to act against his legal duty, he must, based on obligatory precaution, rectify his mistake if possible.

- Ayatullah Sistani, Practical Laws of Islam, Following a Jurist (Taqlid)