Need add more number of "flex-active clicked" on the woocommerce website

I trying to modify much more number of "flex-active clicked" but it's unsuccessful. I think that each number of "flex-active clicked" and "class=clicked" that links to open the relevant slider image of each product that already made by the programmer. The source look like this :

<img src="img/shop-img-2-150x150.jpg" class=" flex-active clicked16" draggable="false" alt="slider image">
<img src="img/shop-img-2-3-150x150.jpg" draggable="false" class="clicked26">
<img src="img/shop-img-2-2-150x150.jpg" draggable="false" class="clicked36">

<img src="img/shop-img-7-150x150.jpg" class=" flex-active clicked15" alt="shop image" draggable="false">
<img src="img/shop-img-7-2-150x150.jpg" draggable="false" class="clicked25">
<img src="img/shop-img-7-1-150x150.jpg" draggable="false" class="clicked35">

How can I add more number of "flex-active clicked" and "class=clicked" for more than 100 product images. I mean number like "16,26,36 and 15,25,35". Any help will be appreciated. Best regards