As the theme is using default Colorbox (or I don't know what it really is using), it doesn't have the image navigation to next picture when you click to enlarge.
I've asked the developer on the possibility of changing it to enable pop up image navigation, and I'm willing to pay for it, and he replied:
I also try change it myself but no avail, the product.tpl seems weird for me (as attached)hi
about colorbox, it's jquery default of opencart.
some popup image the opencart integrated it,
sorry, it's very difficult for your idea, i don't have idea for this issue
What I've tried previously:
However, the site makes no changes.
Anyone can help on this?