Two quick comments:

A search for 'sync' will give lots of earlier topics which you may find useful.

Please add some detail of you situation which is really necessary for any here to give you an answer. eg Source of your audio / video? What camera? What file format? Are you losing sync or is the problem evident when you first import? etc

http://www.magix.info/us/please-do-the-following-before-posting-your-question.forum.621831.html