I hope to have new static resources and images inserted using Tiny MCE default to the selected media source. The system default media source overrides the context settings in both cases. I set media sources for TVs and that works just fine.
I am guess that there is not a way to set a default media source for a context that works for static resources or images added via the rich text editor.
I suppose you will have to put all of the static files in one media source and use if for all contexts. For security, you can put them outside your public site so no one gets any files they shouldn’t
Does the TinyMCE extra you’re using have a system setting for which media source to use? You may need to set that as well if the extra isn’t reading the system default.