Itinerary changes international flights

I’ve noticed more and more in the last few years that there are frequent major itinerary changes for our international flights. The most recent of which required a call and rebook because we wouldn’t make the connection. This is the 4th itinerary change since booking 3 months ago. Any of you travel pros have tips for avoiding this in trips going forward? Is there a timeframe in which they stop the major flight changes prior to trip? I assume they open lots of flight times and then consolidate flights leading up to the date. Just curious if there is a way to avoid this to stop the time consuming calls to airline. (Tried to rebook online it was not an option).