not really! after you change the present, now you can go back to past and see every event as a necessary event that allowed you to feel grateful right now. your past had to be exactly like that for you to be able to feel gratitude at this moment. if things were slightly different you might have felt different.
you just edited the past. once you edit the past and feel great about it now your future will mimic that. you will always be in positive mood and bringing the best future.