This might sound dumb but I'm completely lost about how to save or go back and redo my choices, they all remain the same and I don't know what to do. I got a dead end and now I'm stuck. Can you please help ?
If you enter a new file, you should be able to select your choices in the visual novel itself until you have selected all options that change TRUST values. From that point on, you will be able to select choices on the flowchart itself (this is to prevent people switching options but never seeing the event that happens after they pick an option). The help button on the flowchart explains how the flowchart works, hopefully it may be of further help!