A link to your site, please.
I don’t see any :hover definitinon in your CSS that would cause the submenus to appear on hover.
I also see two javascript errors;
custom.js?ver=4.5.2:544 Uncaught TypeError: $ is not a function
jquery.js?ver=1.12.3:2 Uncaught Error: Syntax error, unrecognized expression: a[href*=#]
this leads me to believe your theme is out of date.
As your theme is a commercial theme, check with the authors to obtain an update. Unfortunately, I just checked themeforest and saw “This item is no longer available”.
Time for a new theme or to hire a developer to update this one.