Storing selected colors in Apple Notes

I know how to highlight text in Notes, press Shift-CMD-C to open the color function, and then use the various options to color my text. But it would be really convenient if I could store favorite colors. I noticed there is a table that has cells, and some of these cells are empty. But I cannot figure how to store a selected color into one of these empty cells. Anybody know how to do this?

BTW, you can see the first 5 cells on the top-left already have colors in them. I don't remember how I got those colors there, or even if that setting is a default.

Thanks for your help.