At the Bible Study we are doing called " The Footprints of God, Mary the Mother of God", a question came up as to belief in apparitions such as Fatima. When the Church approves an apparition, are all Catholics required to believe in it?
No, no one is required to personally accept private revelation. No private revelation is considered necessary for salvation. When the Church approves a private revelation She is saying that it contains nothing contrary to the faith and the apparition/event/situation appears to human reason to be of supernatural origin.
We should not simply reject them as not useful even though they are unnecessary. They can be quite useful in refocusing our attention, actions and prayer life to areas that we have neglected. It is ultimately up to each individual to prayerfully reflect on approved private revelations and determine in good conscience whether it is useful or convincing to him or her.