PIANO CHORD DIAGRAMS

After downloading the set of piano chord diagrams from a user mentioned in December 2022, which comprises of root chords only, I wanted to make inversions and slash chords of my own and insert them in the transcriptions that I do for all my students. I know how to get stuff into palettes etc so my question is, WHY does the diagrams not load as you see them in the score, into the palette? What goes across to the palette each time, is the wwWB|wwB| which is the keyboard shortcuts you have used to make the chord diagram. I cannot for the life of me get the pictures (see png below) to move over into the designated palette.

I also need to know what the default folder in Musescore is within which the .mpal files are stored and how to edit them eg. I want to get rid of the awful black vertical line in the attached diagrams but don't know how. I would also like to use colour dots as opposed to black and white. Any help would be so greatly appreciated.

Lastly, how does one set the little diagrams automatically to be a certain size?