re-colorize some dots - how to do that!?

[denzjos]

Because quality of the drawing is poor, try to darken the dots :  Colours / Threshold (play with the slider to make the dots dark grey / black) .Then add an alpha chanel to the drawing and use 'Colours / Colour to Alpha' to remove the black colour. Add a new layer below the drawing (use another color than white) and set this layer as active. Just colour the dots on this layer with the pencil tool. Because the dots on the upper original layer are now transparent, just the dots seem to have a new colour.