Constellation Web
Click on the previously created note. An inline color palette will pop up. Select the color from the palette. The note color you have selected will be reflected in the note. The new color will stay for all new notes until you change it. The new color will not affect any notes you already made.
Constellation Application
Tap the previously created note. An inline color palette will pop up. Select the color from the palette. The note color you have selected will be reflected in the note. The new color will stay for all new notes until you change it. The new color will not affect any notes you already made.