First, exactly which version and edition of Movie Studio do you have? If it is version 18 or later, please read on; if it is version 17 or older please see this post and follow the advice given there.
Second, please tell us about your computer. This post will show you the level of detail we really need! Please try and ensure you supply ALL the information requested there!
Third, please tell us about the video files you are using in your project. This tutorial will show you how to download, install and use the free MediaInfo utility to analyse at least one of your video files.
Fourth (sorry about this long list) assuming you are using a recent version of MS, please show us a screenshot of the File>Settings>Program (shortcut Y)>Device Options tab.
And finally, can you also make a screenshot of the Export screen settings that you are using?
Thank you for doing all this! It is quite a lot of work but if we, fellow-users, are to have any chance of being able to offer any useful assistance, we really do need this information!