What version of Premiere Elements are you using and on what computer operating system is it running?
What is your project preset? See Edit Menu/Project Settings/General and the readings for Editing Mode, Timebase, Frame Size, and Pixel Aspect Ratio.
What are the properties of your source media? Brand/Model/Settings of the camera that recorded the video or whatever you have on that Timeline?
Did the preview in the Edit area monitor of the rendered Timeline look OK before you headed for the sharing area where Facebook and YouTube is located?
What is the duration of the Timeline?
What were the presets that you used for the uploads to these sites?
What was your choice including settings when you decided to save your Timeline as a file to the computer hard drive?
We need to decide if the problem resides
a. the way you set up the project
b. what you have on the Timeline
c. your computer - resources, video card/graphics card - no QuickTime installed on computer - not running program as Administrator - etc.
If this were a YouTube and Facebook upload problem I would suggest the export of the Timeline to a file which is uploaded to one of these sites
at the site's web site. But, your problems appear to be in the Timeline (as least from what I have read of your description of your issue).
Please supply the requested information, and then we will decide what next.