If you are in the United States in a valid immigration status and want to change your status, there are two ways to do so. One is by application to U.S. Citizenship and Immigration Services (USCIS). The other is by international travel. You must be either a continuing student or a newly admitted for an upcoming semester to change your status through ISSS. Current students must show their transcripts and future students must show their letters of admittance. Further, all students wishing to change status to F-1 or J-1 must show proof of financial support for a year.
Find information on how to change your status to F-1
Find information on how to change your status to F-2
Find information on I-20 Changes & Corrections of level.