Before changing anything I suggest that you activate Child theme and make all modifications in Child theme instead on actual theme. You can read in Documentation how to override and customize Image slider element (Section Customizations -> Customizing Content Elements).
Slider is loading “full” size of the image. You can change that it load some other size (like ‘thumbnail’) in “wp-content / plugins / elvyre-core / includes / content-manager / image-slider”, line 44:
$image_url = wp_get_attachment_image_src($image, 'full');
If you are adding text/links through WordPress Editor, why don’t you just change the color of link or maybe make it bold (check screenshot).