Just curious, I've read the latin-1 copyright character \251 is invalid in ASCII or UTF-8. G'MIC quick copyright on Linux works fine for me using \251 for the copyright symbol.

A few questions, will \251 work for G'MIC quick copyright on all platforms and can G'MIC quick copyright hold settings or does G'MIC reset everytime Gimp relaunches?

The plug-in remember the last parameters you've entered for a filter during a single GIMP session.
Once GIMP quits, your parameters will be reset.

To keep your parameters for a long time, it is suggested to :
1. Choose your filter, set your parameters.
2. Then, press the 'Faves' button to remember the filter and he settings you've just set.

It creates a new 'Fave' filter with your own settings, so you can easily use it afterwards.

Thanks David a two-for answer and I just asked a question about the Faves menu as well in another thread. Just ignore it.