How to set a colour label to a card?
To set a colour label to a card, first, click on the card to open the Card Details. Then click Add colour label located at the top left corner of the panel. Here you can choose up to ten colour labels from the drop-down list.
To change the text of a label, click on the Edit colour labels button at the bottom of the drop-down list.
Click on the necessary label to change its text and then hit Enter on your keyboard. You can also remove text from the label and save it as empty.
Tip: Remove toggle from a checkbox opposite to colour if you do not want to use this colour on your board. This colour will not be displayed in the drop-down list of colour labels.