Application Name: Deluge
Application Site: http://deluge-torrent.org/
Docker Hub: https://hub.docker.com/r/linuxserver/deluge/
Github: https://github.com/linuxserver/docker-deluge
Please post any questions/issues relating to this docker you have in this thread.
If you are not using Unraid (and you should be!) then please do not post here, instead head to linuxserver.io to see how to get support
GTK is Gnome Toolkit which is a Linux thing and not related to what you need.
Easy,
Stop the container, go into your appdata deluge folder and edit the auth file, if you're using Windows then DON'T use notepad, instead install Notepad++ and ensure that line endings are set to Unix like in the picture here (red square bottom right)
Add a line in this format, the number at the end denotes the authentication level as described here.
user:password:10
so for you