Locking Thumbnail
If you deliver to Vevo via feed locking the thumbnail will stop it from being overwritten by further updates.
Vevo
1. Go to Videos
2. Search for the video of the thumbnail you wish to lock
3. Click on Thumbnail
4. Click on upload
5. Select your desired image
6. Drag highlighted element if you wish zoom in on the image
7. Click on Save
8. Click on Publish to update the image an lock the thumbnail