using Python, having a user-def. function, how can I edit a data in a .txt file by another?

Question

In a program task.manager.py that I' m writing, I do need to edit some data in a .txt file but my program fail. I've tried alternative solution but can't identify the issue. Can you please help me?

Here the piece of code failing:

def view_mine():
    
    tasks = []

    with open("tasks.txt", 'r+') as tasks_file: 

        for line in tasks_file:
            user, title, description, due_date, assigned_date, is_completed = line.split (';')

            if username == user:
                tasks.append((user, title, description,due_date, assigned_date, is_completed.strip()))

    if tasks:

        for index, task in enumerate(tasks, start=1):
            user, title, description,due_date, assigned_date, is_completed = task
            print (f"""
            Task number: {index}
            User: {user}
            Task name: {title}
            Task description: {description}
            Due date: {due_date}
            Assigned date: {assigned_date}
            Task completed: {is_completed}
            """)


        choice = input("Please enter the task number you want to work on (-1 to go back to the main menu): ")
        
        if choice.isdigit():
            choice = int(choice)

            if 1 <= choice <= len(tasks):
                task = tasks[choice -1]
                mark_complete = input ("Do you want to mark this task as complete? (Yes/No): ")

                if mark_complete.lower() == "yes":
                    task = list(task)
                    task[5] = "Yes"
                    tasks[choice -1] = tuple(task)
                    print ("Task marked as complete!")

                else:
                    edit_task = input("Do you want to edit this task? (Yes/No): ")

                    if edit_task.lower() == "yes":
                        new_user = input("Please enter the new username for the task: ")
                        new_due_date = input("Please enter the new due date for the task: ")
                        new_assigned_date = input("Please enter the new assigned date for the task: ")
                        task = list(task)
                        task[0] = new_user
                        task[3] = new_due_date
                        task[4] = new_assigned_date
                        task[choice - 1] = tuple(task)
                        print("Task updated!")

When editing a data, I expect the .txt file updated with the new data. But doesn't work.