Dear Sir/Mdm, May i ask you how can I change the “start …

You can add custom CSS to your theme to style HD Quiz however you like.

Button for HD Quiz use the classname hdq_button, so something like .hdq_button {background-color: blue !important;} will change the colour for you. You want to replace “blue” with whatever the HEX value of your blue is though.

If not, you can always consider purchase of the Syler Addon: https://harmonicdesign.ca/product/hd-quiz-quiz-styler-addon/

That page also contains a quick demo/tutorial video showing you all of the cool things you can do with it