Hi Alp,
suppose your usertask name is 'step1_approve'
In user task you can configure two microflows
1)assignment microflow (which sets the target user)
2) after create microflow (where you can set assignee or do something else also)
In the after create microflow retrieve by xpath completed state usertaskview entity object of same name step1_approve (as they are not maintaining completed state usertask entity object as far as i remember ) if it retrieve then also retrieve its list of assigned user and put same assigned user in current in progress state step1_approve task.
If it doesn't retrieve then do nothing as it means first time usertask is being created