Variables Color Fields


I want to create a background whose colors can be configured by zone (example: The top banner -> Choice between white and black; the central part -> Choice between blue, white, black ... Etc ...).

For this, I made the background with Shapes to which I must assign a variable that can be changed via a button type command, to vary the color of this area.

I have already preset colors in "Globals" and created a retractable control panel on which all the colors available by area are displayed.

The user can display the colors panel via a discreet button then, on this panel, he will have for each field a limited number of color choices (in the form of small boxes on which to press) to vary the color of the area indicated.

I specify that the choices are limited, for each zone there will be visually 2 or 3 or 4 colors available only.

So I have 2 problems:

1 - How to create / assign a color variable to each shape so that the defined color corresponds to a choice?

2 - How to create a command other than an ON / OFF button, which can activate the coloring of the shape according to the previous variable?