Faith On The March and the Proclaimers book https://wol.jw.org/en/wol/d/r1/lp-e/1101993012
When I encountered criticism while preaching my response was always: The bible says that God's light will gradually get brighter and brighter. This means that there are beliefs that the Jehovah's Witnesses have abandoned and we make changes as necessary. We don't mind adapting whenever we see new truths. I also used Acts chapter 1 to show that even the disciples had incorrect ideas about God's kingdom.
When facing criticism of 1914 I used to explain : Yes, we know that secular chronology does not coincide with ours but we feel that ours better fits with biblical chronology. Besides, secular chronology is not always accurate. (In reality the evidence against 1914 is very, very solid. We choose to stick to our teaching about it even though it's flawed).
Another explanation I used to give: they were not perfect men. They made mistakes just like anyone else. And again I would show Acts chapter 1 to show that even the disciples had flawed ideas about the kingdom of God.
So yeah, I was a very faithful Jehovah's Witness and eagerly defended the beliefs. There were plenty of things that led me to leave.