If i understand correctly, that is the only way to actually “save” a background image. there is no background image library and you have to upload each time.
Not what asked, but still may be useful.
Since ManyCam 7.7 there is copy/paste layer feature: use Ctrl+C/Ctrl+V (Cmd+C/Cmd+V on macOS) to copy selected layer and past on same/another preset.
Can be very convenient if you want to setup Chroma Key once and use many times.
I use all 24 presets to produce our church services, with each preset representing a different segment of the service such as liturgy, hymns and the sermon - all with one of 7 different camera views as PIP inserts.
The structure of the service changes dramatically from season to season, as it does when there is a wedding, funeral or other streamed event. I have to delete all of the 24 presets and rebuild them for each new service structure.
My suggestion is that ManyCam incorporate the ability to save all of the current presets as a reloadable project. This is analogous to most video editing software, for instance. This would also help with some of the issues folks in this thread are recommending and bring ManyCam into a more professional project oriented category of software.
I reckon many of us have been asking for this very same functionality for a long time.