Sub Palette

I apologize for all the questions, I promise I try to look these answers up myself via google and/or YouTube, it just seems a lot of things get glossed right over with no real explanation.

I am trying to understand Sub 1, Sub 2, Sub 3, and Sub 4 pallets in the when it comes to coloring a sprite or background. When I make a change to Sub 2, 3 or 4 it changes all the Sub palette groups.... I just don't understand how to correctly use these. Can someone please explain the mechanics behind this and/or point me to a comprehensive article about them?

What I do understand, is that we can only use 3 colors (well 4, but black will always be the transparent color as I understand it). I also understand that we build the sprites in black, red, green, and blue, and then we map those colors to a different color. I am sure the answer to my question lies somewhere in between this and something else (I just haven't put that piece of the puzzle together).

Thanks in advance for your help.

Here's the "Orientation" video explains everything about NESmaker: https://youtu.be/yP6Crmyxcbk
Then, I really suggest to watch the tutorials from the official website: https://www.thenew8bitheroes.com/learn

But basically...
"Sub 1", "Sub 2" "Sub 3" and "Sub 4" are four slots of color sub palettes that can be use for your sprites, on a screen.
For each "slot", you can assign a sub palette (by using the selection combobox). A sub palette is composed of 3 colors + 1 transparent color (the first color of the sub pal).



Each sub palette can have their 3 colors set differently.

I was just about to say pretty much everything above but also, note that your background colour doesn't HAVE to be black.
And also, colours have to be set in your screen settings to come into effect.

The orientation video explains palettes very well.