If you have gone down the ADI route then you can only do what the options let you and if you want more help with this, then you would be better suited going through Wix Support.
https://support.wix.com/en/article/contacting-wix-customer-care-for-support
Again if you are using Ecommerce for Wix Stores, then you can only change so much of that as it is an app from Wix and again, if you want more help with this then please go through Wix Support.
https://support.wix.com/en/article/customizing-your-wix-stores-product-page
If you had the option of using code, then you could do it through the use of style on the buttons.
https://www.wix.com/corvid/reference/$w.Button.html#style
Your code would look something like this…
//rest of code//
$w("#button2").style.backgroundColor = "#384AD3";
$w("#button2").style.color = "white";
$w("#button8").style.backgroundColor = "#384AD3";
$w("#button8").style.color = "white";
$w('#button8').label = "WAIT!";
//rest of code//