To change the width infowindow of the marker, please follow the steps below.
Open the theme CSS editor, select Appearance Editor, select style.css.
Image of WordPress Theme Editor
Paste this CSS below into your style.css and click Update File.
body #asl-storelocator.asl-p-cont .infoWindow {width: 400px !important;}
#asl-storelocator.asl-p-cont div.arrow-down {margin-left: 166px !important;}
Use this shortcode with the same width value, which you have used in the CSS for the width, in our example, it is 400px, and save it, refresh the page to see the changes, please make sure you have installed version 4.5.8 or above, in case of older version, please upgrade it.
[ASL_STORELOCATOR infobox_width="400"]
Once you have saved the shortcode and the CSS, refresh the page to see the change.