Try this: https://www.youtube.com/watch?v=Bn9_UomRv8s
Yes, I know it is a Justflight 757 however, I am nearly certain it WILL work for the QW 757 and the Freeware 767 *.mdl.
Make sure you have followed every step precisely.
It should be in the linked video.
By the way: DON'T put your 767 model into the QW. Instead, replace the QW Panel, Sound (Optional) and VC mdl file into the 767 Freeware.
I hope it helped:)
Neel