Thanks for the screenshot I have understood your issue.
Now, In order to solve your issue simply go to the Dashboard >> XStore >> Theme Settings >> Theme Custom CSS >> Global and paste the below code at the bottom of the CSS box there.
.et-menu-list .subitem-title-holder a:before{background: black !important;}
Then save settings and check back to your site after clearing the browser cache.
Note: in the above code the word “black” is the color you can change it with you want.
