Colour Formats

I like to colour code note entries as I add or adjust them into a score as an arrangement progresses. However, when I go to Export and although Ive reset all the colours in the Musecore file to black, they export as multi coloured in the pdf. Hoping that someone might be able to point me in the right direction to correct that! Many thanks in advance!
(the left hand image is Musecore and the right the pdf of the part)