The smallest changes in Avengers: Endgame with the biggest repercussions

Two ideas come to mind:

1- The first adjustment is nothing more than a way to make the central part of the film more lively (in terms of action scenes and perception of danger by the Avengers and the viewer).

I would have made Thanos aware of the Avengers’ intent to undo his work, in all times and places they go, not just on Morag in 2014.

This simple change would have led to a drastically different time travel.

We could have seen Professor Hulk, Iron man, Ant man and Captain America ally with the Avengers who were in New York in 2012, especially with the Ancient One, which would have led to some very interesting action scenes.

Imagine: Thanos arriving in New York in 2012 …

… and the Avengers of the future who promptly join forces with confused past versions of themselves …

… Taking time until Professor Hulk returns with the Ancient One.