Replacing media cover images in Sonarr 4

Sonarr version (exact version): 4.0.1.929
Mono version (if Sonarr is not running on Windows):
OS: Windows 10
Debug logs:
Description of issue:
I used to be able to manually replace posters, banners and fanart images for shows and Sonarr would keep these images. In version 4 Sonarr is overwriting my images whenever the show is refreshed. Is there a way to use artwork images other than the first in each category at TheTVDB?