I made a mistake. I need to change my 2018 full time student status to part time student status. I don't know how to fix it?

If this is a dependent, Click on forms on the upper right, click on the dependents  worksheet on the left , make your corrections for line E.  If it's you, look at the Personal Info worksheet for you and change this under Part II

Then also click on and look at the student Info worksheet to see if there's anything you need to change.