If you have a psychic vision and you do not like the circumstances that have occurred, can you either prevent it from happening or modify it till it's not as serious? Do you have to know where the vision takes place in order to go in and change it? If you go into a vision to change it, can you injure your astral or physical body?
Of course you can change it. The future is not set, and we do not know what the future will hold. Usually, what you are seeing is what will happen if a change is not made. Now, I wouldn't think that going into the vision astrally is going to change anything. try to determine what is the cause behind the circumstances in the vision and make a change.