What version of Premiere Elements and what computer operating system?
What are the properties of these videos which you appear to be importing into a Premiere Elements project?
Brand/model/setting for the camera that recorded the video?
When you import the video and drag it to the Timeline for the first time, is there no colored line over its content, orange line, green line?
Do you attempt to do Timeline render of the Timeline content if line is orange, using
a. Timeline Menu/Render WorkArea
b. Render button above Timeline
c. Pressing the Enter key of the computer main keyboard?
What did you manually or the project automatically set as the project preset (project settings) for the project in order to match the properties of the imported files. If you do not know, please tell us what you see for Editing Mode, Timebase, Frame Size, and Pixel Aspect Ratio under Edit Menu/Project Settings/General.
Let us start here and then decide what next based on the details in your reply.
Any question or need clarification, please do not hesitate to ask.
Add On...Since you did not give details, my question details are based on version 11, 12, 13, or 14 on Windows 7, 8, 8.1, or 10 64 bit.