Whatever the big change in your world, do the majority of the population welcome or fear it? Where there is change, there is usually resistance to that change so how does that happen in your settings?
What are the triggers for the big changes to happen? Where time travel is a possibility, does someone use that to try to fix the results of the big changes? Does it work? What are the consequences? How does the media on your world report the triggers/big changes etc or can they only write what they are told to write?
And when people(s) are agitated, how do they express that? Riots? How are things calmed down (if they are at all)? What is the outcome of the historical changes?