How to change the color of the values in Stacked Graph?

[#1]

Hello All,

I need to change the color from black to white in the values which i got by stacked graph

Values in the graph:99.28% and 99.19% [ i need to change the color from black to white]

Dimension 1:  if(match(question_id,'Q1','Q2'),if(question_id='Q1','GOOD IMPRESSION',if(question_id='Q2','SUCCESSFUL IN EDUCATING')))

Dimension 2: if((Match(answer_text,'Strongly Agree','Excellent')),'Strongly Agree',if(Match(answer_text,'Agree','Above Average'),'Agree'))

Measure: count(distinct{<question_id={'Q1','Q2'}>} lender_offer_id)/count(distinct {<question_id={'Q1','Q2'}>} total lender_offer_id)