What computer operating system is Premiere Elements 12 running on?
What are the properties of the video that you have imported into your Premiere Elements 12 project? And, what have you or the program set as the project preset?
(See Edit Menu/Project Settings/General and its Editing Mode/Timebase/Frame Rate/Pixel Aspect Ratio readings (even if they look grayed out).
What type of an export are you requiring?
Looking forward to your follow up.