First, open your tQSL cert application
Click on file, and load certificate
Choose your tq6 file and follow the next instructions. Once you have done, you will see your callsign without the read cross mark on the medal logo.
For more info, please read http://www.arrl.org/files/file/LoTW%20Instructions/Load%20and%20Save%20Your%20Certificate_731.pdf