I have a flexi task and assign 3 persons. Is it possible to create flexi task for each person?
I mean I need to create each time flexi task for each user.
If you tick the "Create individual tasks..." setting on the task (see below), you should be generating individual tasks for each member of the assignees. The one caveat to this is if you are send the message to a Distribution list group email. This will not generate individual tasks as the DL is a single entity. All people in the group will get an email, but there will only be one task.
The parallel action will work. If you are needing the same flexi task but a different form for each user, you could create rules that show or hide panels based on the user or some variable.
You can have different forms for each user but they can point to the same list. The workflow is pointing to the same list and can check the user and run steps based on that user.
Running it in parallel allows you to create specific tasks for each user. This is the most straightforward way of accomplishing what you are looking for, but keep in mind that if there are more (or less) than the 3, you would need to account for that.