Reason: This appears to be a design issue with Turnitin's website. Turnitin's Submit File window does not seem to take the browser font size into account, and is set to a fixed height regardless of font size. If a user has set their browser font size to anything larger than the default, the Submit button may be cut off the screen with no way to scroll down.
Solution: Currently the only fix to this problem is to change the browser's font size back to the default size. We have contacted Turnitin to make them aware of this design issue.