Hey @miauy
That is coming from your data and part of the “Data Label” of the visual so you won’t be able to change it. You could create a calculated field using ifelse to change the 1/0 to “Yes”/“No” or you could remove the data label and create a custom legend (legends in quicksight have pretty limited editability unfortunately).
For a custom legend you would create a text box and format the text to match your data colors in your target visual.